Search

Background: The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic disrupted respiratory syncytial virus (RSV) seasonality. To optimize the use and evaluation of RSV infant immunization strategies, monitoring changes in RSV epidemiology is essential., Methods: Hospitalizations for acute respiratory infections (ARIs) and RSV-coded ARI in children <2 years were extracted in 4 European hospitals, according to predefined case definitions (International Classification of Diseases, Tenth Revision codes). Prepandemic RSV seasons (2017-2018 to 2019-2020) were compared to 2021-2022 and 2022-2023., Results: In 2021-2022 and 2022-2023, the peak number of RSV hospitalizations was higher than prepandemic peaks after short periods of RSV circulation, and lower than prepandemic peaks after long periods of RSV circulation. A greater proportion of RSV hospitalizations occurred in children 1 to <2 years in 2021-2022 in the Netherlands (18% vs 9%, P = .04). No increase in age was observed elsewhere. High-risk children represented a greater proportion of RSV hospitalizations during the pandemic. The proportion of pediatric intensive care unit admissions did not increase., Conclusions: A decrease in population immunity has been linked to older age at RSV hospitalization. We did not observe an increase in age in 3 of the 4 participating countries. Broad age categories may have prevented detecting an age shift. Monitoring RSV epidemiology is essential as Europe implements RSV immunization., Competing Interests: Potential conflicts of interest. J. G. W. has been an investigator for clinical trials sponsored by pharmaceutical companies, including AstraZeneca, Merck, Pfizer, Sanofi, and Janssen, and participated in the advisory boards of Janssen and Sanofi and was a speaker at a Sanofi sponsored symposium (all fees/honoraria were paid to UMCU). T. H. has received honoraria for lectures or participation in advisory boards or data monitoring committees from Janssen, Sanofi, Enanta, MSD, Pfizer, Moderna, and Shionogi. A. D.-U. participated in clinical trials for vaccines, monoclonals, and antivirals for RSV as a subinvestigator. All honoraria were paid to the institution. F. M.-T. reports honoraria from GSK, Pfizer, Sanofi Pasteur, MSD, Seqirus, Biofabri, and Janssen for taking part in advisory boards and expert meetings and for acting as a speaker in congresses, outside the submitted work; and principal investigator role in randomized controlled trials for GSK, Pfizer, Sanofi Pasteur, MSD, Seqirus, Biofabri, Janssen, Ablynx, Gilead, Regeneron, Roche, Abbott, Novavax, and MedImmune, with honoraria paid to his institution. S. C. has provided consultancy or investigator roles in relation to product development for Ablynx, Janssen, MedImmune, AstraZeneca, Pfizer, GSK, Vertex, AbbVie, and Boehringer Ingelheim, with fees paid to the University of Edinburgh. L. J. B. has regular interaction with pharmaceutical and other industrial partners. He has not received personal fees or other personal benefits. UMCU has received major funding (>€100 000 per industrial partner) for investigator-initiated studies from AbbVie, MedImmune, AstraZeneca, Sanofi, Janssen, Pfizer, MSD, and MeMed Diagnostics. UMCU has received major funding for the RSV GOLD study from the Bill & Melinda Gates Foundation. UMCU has received major funding as part of the public-private partnership IMI-funded RESCEU and PROMISE projects with partners GSK, Novavax, Janssen, AstraZeneca, Pfizer, and Sanofi. UMCU has received major funding by Julius Clinical for participating in clinical studies sponsored by MedImmune and Pfizer. UMCU received minor funding (€1000–€25 000 per industrial partner) for consultation and invited lectures by AbbVie, MedImmune, Ablynx, Bavaria Nordic, MabXience, GSK, Novavax, Pfizer, Moderna, AstraZeneca, MSD, Sanofi, Janssen. L. B. is the founding chairman of the ReSViNET Foundation. All other authors report no potential conflicts. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed., (© The Author(s) 2024. Published by Oxford University Press on behalf of Infectious Diseases Society of America.)

Lower respiratory tract infections, commonly caused by respiratory syncytial virus (RSV) or Streptococcus pneumoniae (pneumococcus), pose a substantial global health burden, especially in children younger than 5 years of age. A deeper understanding of the relationship between RSV and pneumococcus would aid the development of health-care approaches to disease prevention and management. We completed a systematic review to identify and assess evidence pertaining to the relationship between RSV and pneumococcus in the pathogenesis of childhood respiratory infections. We found mechanistic evidence for direct pathogen-pathogen interactions and for indirect interactions involving host modulation. We found a strong seasonal epidemiological association between these two pathogens, which was recently confirmed by a parallel decrease and a subsequent resurgence of both RSV and pneumococcus-associated disease during the COVID-19 pandemic. Importantly, we found that pneumococcal vaccination was associated with reduced RSV hospitalisations in infants, further supporting the relevance of their interaction in modulating severe disease. Overall evidence supports a broad biological and clinical interaction between pneumococcus and RSV in the pathogenesis of childhood respiratory infections. We hypothesise that the implementation of next-generation pneumococcal and RSV vaccines and monoclonal antibodies targeting RSV will act synergistically to reduce global morbidity and mortality related to childhood respiratory infections., Competing Interests: Declaration of interests LB and RD obtained a research grant from the Investigator-Initiated Studies Program of Merck Sharp & Dohme (MSD) to cover the costs of Violicom's searches and screening of the data. LB is the founding chairman of the Respiratory Syncytial Virus Foundation (ReSViNET Foundation); he has regular interactions with pharmaceutical and other industrial partners, but he has not received personal fees or other personal benefits. LB reports the following funding to his institution: funding for investigator-initiated studies from AbbVie, MedImmune, AstraZeneca, Sanofi, Janssen, Pfizer, MSD, and MeMed Diagnostics; funding for the RSV GOLD study from the Bill & Melinda Gates Foundation; funding as part of the Innovative Medicines Initiative-funded RESCEU and PROMISE projects with partners GSK, Novavax, Janssen, AstraZeneca, Pfizer, and Sanofi; funding for participation in clinical studies sponsored by MedImmune and Pfizer from Julius Clinical; and consulting fees and fees for invited lectures from AbbVie, MedImmune, Ablynx, Bavaria Nordic, MabXience, GSK, Novavax, Pfizer, Moderna, AstraZeneca, MSD, Sanofi, and Janssen. AM has received research grants to her institution from Janssen, Merck, and the US National Institutes of Health (NIH); fees for participation on advisory boards from Janssen, Sanofi Pasteur, Merck, Pfizer, and AstraZeneca; and fees for lectures from Sanofi Pasteur and AstraZeneca. OR has received research grants to his institution from Janssen, Merck, NIH, and the Bill & Melinda Gates Foundation; fees for participation on advisory boards from Sanofi Pasteur, Merck, and Pfizer; and fees for lectures from Pfizer, Sanofi Pasteur, and AstraZeneca. DMW is supported by a grant from the NIH National Institute of Allergy and Infectious Diseases (R01AI137093) and has received consulting fees from Pfizer, Merck, and GSK/Affinivax for work unrelated to this manuscript; he is the principal investigator on grants from Pfizer and Merck to his institution for work unrelated to this manuscript. RD has received grants to his institution from Pfizer, MSD, and MedImmune/AstraZeneca; consulting fees and fees for participation on advisory boards from Pfizer and MSD; payment for speakers bureaus from Pfizer, MSD, Sanofi Pasteur, and GSK; and payment for expert testimony from Pfizer. SBB and DB declare no competing interests., (Copyright © 2024 Elsevier Ltd. All rights reserved, including those for text and data mining, AI training, and similar technologies.)

Introduction: Respiratory syncytial virus (RSV) causes acute respiratory tract infection (ARTI) and reinfects adults throughout life, posing a risk for hospitalization in older adults (>60 years) with frailty and comorbidities., Methods: To investigate serum and mucosal antibodies for protection against RSV infections, baseline serum samples were compared for RSV-pre- and -post-fusion (F) binding, and RSV-A2 neutralizing IgG antibodies between symptomatic RSV-ARTI ( N = 30), non-RSV (RSV negative) ARTI ( N = 386), and no ARTI ( N = 338). Mucosal RSV-pre-F IgA and IgG levels, as well as serum RSV-G IgG antibodies, were analyzed to determine their association with protection from symptomatic RSV-ARTI in a subset study., Results: Using a receiver operating characteristic (ROC) analysis, we established thresholds of 1.4- to 1.6-fold change (FC) for RSV-pre-F and -post-F, and RSV-A2 neutralizing IgG antibodies, respectively, enabling the identification of asymptomatic RSV cases with high sensitivity and specificity (>80% and >90%, respectively). As a result, serum RSV-pre-F, RSV-G IgG, and mucosal pre-F binding IgA antibodies showed correlations with protection against symptomatic RSV infection. RSV-pre-F IgG antibodies were correlated with protection from RSV infections irrespective of the symptoms., Discussion: This study provides insights into antibody-mediated protection for symptomatic RSV infection in a community-dwelling older-adult population and establishes a threshold to identify asymptomatic RSV infection using a data-driven approach., Competing Interests: DÖ, SB-J, MC, AB, KT, SO, and JA were employed at the time the work was performed by Janssen Pharmaceuticals, a Johnson & Johnson company, and may be Johnson & Johnson stockholders. CV and AM were employed by Sanofi at the time the work was performed and may be Sanofi stockholder. CV is now employed by Vaccines Europe, Brussels, Belgium. BS and JD are employed by GlaxoSmithKline and may be GlaxoSmithKline stockholders. CB has participated in two virtual Advisory Boards for Moderna relevant to RSV vaccination on 30 March 2023 and 18 May 2023 and received payments. TV has received grant from Innovative Medicines Initiative European Commission, in which Biomerieux, Abbott, BD, BioRad, Janssen contributed ValueDx project, NIHR for project on cellulitis, and NHS UK regional funding for project on respiratory tract infections. He have been on the Advisory Board of a US study on lower respiratory tract infections in primary care EAST-PC funded by the Agency for Healthcare Research and Quality. He is a member of the Dutch Health Council. SD has provided consultancy and/or investigator roles in relation to product development for Janssen, AstraZeneca, Pfizer, Moderna, Valneva, MSD, iLiAD and Sanofi with fees paid to St George’s, University of London. SD has been on the RSV advisory board Sanofi Pasteur and received fees. SD also received support for travel for chairing a conference session, fees paid to his institution SGUL. SD is a member of the UK Department of Health and Social Care’s DHSC Joint Committee on Vaccination and Immunisation JCVI RSV subcommittee and Medicines and Healthcare products Regulatory Agency’s MHRA Paediatric Medicine Expert Advisory Group PMEAG. JW is investigator for clinical trials funded by pharmaceutical companies including AstraZeneca, Merck, Pfizer, Sanofi, and Janssen and investigator for clinical trials funded by IMI/Horizon2020 and ZonMw, with payments paid to her institution. She was a speaker at Sanofi sponsored symposium ESPID, payments paid to her institution. JW participated in the advisory board of Janssen RSV older adults and Sanofi advisory board with fees paid to UMCU. AP is part of EC IMI Programme RESCEU, payments paid to his institution. He has received grants from Gates, Wellcome, CEPI, MRC, NIHR, Serum Institute of India, AstraZeneca, and EC, with payments paid to his institution. Oxford University has entered into a partnership with AZ for development of COVID-19 vaccines. AP is a contributor to intellectual property licensed by Oxford University Innovation to AstraZeneca. AP is chair of the UK Department of Health and Social Care’s DHSC Joint Committee on Vaccination and Immunisation JCVI, NIHR Senior Investigator, member of the Academy of Medical Sciences AMS and was a member of WHO’s SAGE until January 2022. AP’s institution received funding from the European Commission’s IMI programme for the conduct of this study. Oxford University has entered a partnership with AstraZeneca for the development of COVID-19 vaccines. PO received honoraria GSK, Pfizer Inc, Sanofi Pasteur, Seqirus, Moderna and Janssen for participation in advisory boards and expert meetings and for acting as a speaker in congresses outside the scope of the submitted work. PO is also a principal investigator in the INFLAMMAGE trial co-funded by the Medical Research Council UK and GSK as part of the EMINENT consortium to promote inflammation research. He received grants from UKRI-MRC/DHSC NIHR Grant award MR/V027859/1, and UKRI-BEIS for human infection challenge with SARS-CoV-2 and had roles as school governor Sidcot, Somerset. LB has regular interaction with pharmaceutical and other industrial partners. He has not received personal fees or other personal benefits. UMCU has received major funding >€100,000 per industrial partner for investigator-initiated studies from AbbVie, MedImmune, AstraZeneca, Sanofi, Janssen, Pfizer, MSD and MeMed Diagnostics. UMCU has received major funding for the RSV GOLD study from the Bill and Melinda Gates Foundation. UMCU has received major funding as part of the public private partnership IMI-funded RESCEU and PROMISE projects with partners GSK, Novavax, Janssen, AstraZeneca, Pfizer and Sanofi. UMCU has received major funding from Julius Clinical for participating in clinical studies sponsored by MedImmune and Pfizer. UMCU received minor funding €1,000-25,000 per industrial partner for consultation and invited lectures by AbbVie, MedImmune, Ablynx, Bavaria Nordic, MabXience, GSK, Novavax, Pfizer, Moderna, AstraZeneca, MSD, Sanofi, Genzyme, Janssen. LB is the founding chairman of the ReSViNET Foundation. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Öner, Vernhes, Balla-Jhagjhoorsingh, Moureau, Crabbe, Salaun, Bastian, Thys, De Smedt, Ooft, Korsten, Adriaenssens, Coenen, Butler, Verheij, Drysdale, Wildenbeest, Pollard, Openshaw, Bont and Aerssens.)

Rationale: Respiratory syncytial virus (RSV) is a common global respiratory virus that is increasingly recognized as a major pathogen in frail older adults and as a cause of chronic obstructive pulmonary disease (COPD) exacerbations. There is no single test for RSV in adults that has acceptable diagnostic accuracy. Trials of RSV vaccines have recently shown excellent safety and efficacy against RSV in older adults; defining the frequency of RSV-related community infections and COPD exacerbations is important for vaccine deployment decisions. Objectives: This prospective study aimed to establish the frequency of outpatient-managed RSV-related exacerbations of COPD in two well-characterized patient cohorts using a combination of diagnostic methods. Methods: Participants were recruited at specialist clinics in London, United Kingdom, and Groningen, the Netherlands, beginning in 2017 and observed for three consecutive RSV seasons, during exacerbations, and at least twice yearly. RSV infections were detected by RT-PCR and serologic testing. Measurements and Main Results: A total of 377 patients with COPD attended 1,999 clinic visits and reported 310 exacerbations. There were 27 RSV-related exacerbations (8.7% of the total); of these, seven were detected only by PCR, 16 only by serology, and four by both methods. Increases in RSV-specific Nucleoprotein antibody were as sensitive as those in the antibody to Pre-Fusion or Post-Fusion for serodiagnosis of RSV-related exacerbations. Conclusions: RSV is associated with 8.7% of outpatient-managed COPD exacerbations in this study. Antibodies to RSV Nucleoprotein may have diagnostic value and are potentially important in a vaccinated population. The introduction of vaccines that prevent RSV is expected to benefit patients with COPD.

Competing Interests: NH declares grants or contracts from Merck (investigator-initiated) and has participated on an advisory board for CSL-Seqirus. LB declares interaction with pharmaceutical and other industrial partners, but has not received personal fees or other personal benefits; and is the founding chairman of the ReSViNET Foundation. University Medical Center Utrecht has received major funding for investigator initiated studies from AstraZeneca, Sanofi, Janssen, Pfizer, MSD, MeMed Diagnostics, and the Bill and Melinda Gates Foundation; has received major funding as part of the public–private partnership IMI-funded RESCEU and PROMISE projects with partners GlaxoSmithKline, Novavax, Janssen, AstraZeneca, Pfizer, and Sanofi; has received major funding by Julius Clinical for participating in clinical studies sponsored by AstraZeneca, Merck, and Pfizer; and has received minor funding for consultation, Data and Safety Monitoring Board membership, or invited lectures by Ablynx, Bavaria Nordic, GlaxoSmithKline, Novavax, Pfizer, Moderna, AstraZeneca, MSD, Sanofi, and Janssen.

Competing Interests: MP, LG, and SM are employees of Medicines Patent Pool, which is funded by Unitaid, the Swiss Agency for Development and Cooperation, the French Ministry for Europe and Foreign Affairs, the German Agency for International Cooperation, and the Ministry of Foreign Affairs of Japan. HJZ reports grants from the Bill & Melinda Gates Foundation, the US National Institutes of Health, Pfizer, MSD, and Sanofi to their institution, outside this work; and serving on an advisory board for MSD and on the Data Safety and Monitoring Board for Moderna. NIM and JT have received support for attending meetings or travel from the ResViNET Foundation. All other authors declare no competing interests.

Respiratory syncytial virus (RSV) is the second most common pathogen causing infant mortality. Additionally, RSV is a major cause of morbidity and mortality in older adults (age ≥60 years) similar to influenza. A protein-based maternal vaccine and monoclonal antibody (mAb) are now market-approved to protect infants, while an mRNA and two protein-based vaccines are approved for older adults. First-year experience protecting infants with nirsevimab in high-income countries shows a major public health benefit. It is expected that the RSV vaccine landscape will continue to develop in the coming years to protect all people globally. The vaccine and mAb landscape remain active with 30 candidates in clinical development using four approaches: protein-based, live-attenuated and chimeric vector, mRNA, and mAbs. Candidates in late-phase trials aim to protect young infants using mAbs, older infants and toddlers with live-attenuated vaccines, and children and adults using protein-based and mRNA vaccines. This Review provides an overview of RSV vaccines highlighting different target populations, antigens, and trial results. As RSV vaccines have not yet reached low-income and middle-income countries, we outline urgent next steps to minimise the vaccine delay., Competing Interests: Declaration of interests JT and NIM received support for attending meetings or travel from the ResViNET Foundation. UMC Utrecht (LJB and NIM) received grants from AbbVie, AstraZeneca, The Bill & Melinda Gates Foundation, the Dutch Lung Foundation, The Gates Medical Research Institute, GlaxoSmithKline (GSK), Janssen, MedImmune, MeMed, Merck, Novavax, Pfizer, and Sanofi; and payment or honoraria for lectures, presentations, speakers bureaus, manuscript writing, or educational events from AbbVie, Ablynx, AstraZeneca, Bavaria Nordic, GSK, Janssen, MabXience, MedImmune, MEDtalks, Merck, Moderna, Novavax, Pfizer, Sanofi, and Virology Education. LJB is founding chairman of the ReSViNET Foundation. UJB was supported by the Division of Intramural Research of the National Institute of Allergy and Infectious Diseases, National Institutes of Health (NIH); and is named as an inventor on patents for live-attenuated RSV, with royalties paid to the National Institutes of Health by Sanofi Pasteur. ADC received grants from The Bill & Melinda Gates Foundation and WHO. CC received grants from Sanofi Pasteur, the Centers for Disease Control and Prevention, The Bill & Melinda Gates Foundation, and the Task Force for Global Health. RD received grants from Pfizer, Merck, MedImmune, and AstraZeneca; consulting fees from Pfizer, Merck and GSK; payment or honoraria for lectures, presentations, speakers bureaus, manuscript writing, or educational events from Pfizer, Merck, Sanofi Pasteur, GSK, MedImmune, and AstraZeneca; and participated on a data safety monitoring boards or advisory boards for Pfizer, Merck, and GSK. BSG is named as an inventor on patents for RSV vaccines and mABS; received royalties from the NIH; and consulting fees from GSK, Pfizer, AstraZeneca, Sanofi Pasteur, and Exevir. RAK received grants from the NIH and Sanofi Pasteur. YL received grants from GSK, Merck, and WHO; consulting fees from Pfizer and WHO; payment or honoraria for lectures, presentations, speakers bureaus, manuscript writing, or educational events from Pfizer; and support for attending meetings or travel from Pfizer. AJP received grants from The Bill & Melinda Gates Foundation, Wellcome, Cepi, the Medical Research Council, the NIH and Care Research, AstraZeneca, the European Commission, and the Serum Institute of India; royalties from AstraZeneca for the development of COVID-19 vaccines; consulting fees from Shionogi; is chair of the Joint Committee on Vaccination and Immunization of the Department of Health and Social Care; and has been member of the Strategic Advisory Group of Experts on Immunization for WHO. All other authors declare no competing interests., (Copyright © 2024 Elsevier Ltd. All rights reserved, including those for text and data mining, AI training, and similar technologies.)

The current understanding of the RSV-related mortality age distribution in low- and lower-middle-income countries (LMICs) relies on a limited number of disease incidence studies reporting wide age bands, and lacking specificity to Gavi-eligible countries. Understanding the age distribution of RSV-related deaths is crucial for the implementation of RSV interventions in LMICs that rely on support from Gavi. This study aims to provide the age profile of RSV mortality specifically in Gavi-eligible countries. Utilizing data from the RSV GOLD project, an ongoing global online mortality registry focusing on children under the age of 5 with laboratory-confirmed RSV infection, we employed two models (Complete Data Model and Prospective Data Model) to estimate the age profiles. To mitigate biases related to age group representation, we applied post-stratification weighting in our analysis. We included 423 pediatric deaths, including 145 from the community, under 2 years of age from 15 Gavi-eligible countries. Both models identified a peak age at 1 month and found that the majority of RSV-related mortality cases (59-77 %) from Gavi-eligible countries occur before 6 months of life. However, the models exhibited disparities in other age-related metrics. We present fitted age-at-time-of-death probability distributions to aid impact and cost-effectiveness studies. We expect that implementing infant RSV immunization strategies, such as maternal vaccination or infant immunoprophylaxis, will have high impact on RSV-related mortality in Gavi-eligible countries. The divergent results from the two models underscore the importance of carefully considering potential biases in retrospective and surveillance data when interpreting the age profile of RSV mortality cases in future research., Competing Interests: The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: LJB has regular interaction with pharmaceutical and other industrial partners. He has not received personal fees or other personal benefits. The University Medical Centre Utrecht (UMCU) has received major funding (>€100 000 per industrial partner) for investigator-initiated studies from AbbVie, MedImmune, Janssen, the Bill & Melinda Gates Foundation, Nutricia (Danone), and MeMed Diagnostics. UMCU has received major cash or in-kind funding as part of the public–private partnership IMI-funded RESCEU project from GSK, Novavax, Janssen, AstraZeneca, Pfizer, and Sanofi. UMCU has received major funding by GlaxoSmithKline and Julius Clinical for participating in the INFORM study sponsored by MedImmune. UMCU has received minor funding for participation in trials by Regeneron and Janssen from 2015 to 2017 (total annual estimate <€20 000). UMCU received minor funding for consultation and invited lectures by AbbVie, MedImmune, Ablynx, Bavaria Nordic, MabXience, Novavax, Pfizer, and Janssen (total annual estimate <€20 000). LJB. is the founding chairman of the ReSViNET Foundation. NIM has regular interaction with pharmaceutical and other industrial partners. She has not received personal fees or other personal benefits. Cheryl Cohen (C. C. has received minor funding from Sanofi and support to attend meetings from Parexel. Sandra Chaves (S. S. C.) has left the Centers for Disease Control and Prevention and is currently working for Sanofi Pasteur, France. All other authors report no potential conflicts. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed., (© 2024 The Author(s).)

Patient and public involvement in research refers to patients or caregivers with disease experience contributing to the design, conduct or dissemination of results from research. Patient and public involvement has given rise to new fields in healthcare-oriented research and has the potential to transform infectious diseases through interventional trials. Our recommendations and best practices from years of organizing respiratory syncytial virus parent networks are provided., Competing Interests: A.W.L. has previously worked in the pharmaceutical industry, but was not employed in industry while the manuscript was authored and submitted for publication. B.C. is an employee of a for-profit company, Chorus Innovations, Inc. Louis Bont has regular interaction with pharmaceutical and other industrial partners. He has not received personal fees or other personal benefits. Other authors have no conflicts of interest to disclose, (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

Breastfeeding provides important immunological benefits to the neonate, but how the different immunoactive components in breastmilk contribute to immunity remains poorly understood. Here, we characterized human breastmilk T cells using single-cell RNA-Seq and flow cytometry. Breastmilk contained predominantly memory T cells, with expression of immune signaling genes, high proliferation, and an effector Th1/cytotoxic profile with high cytokine production capacities. Elevated activation was balanced by an enriched Treg population and immune regulatory markers in conventional memory T cells. Gene and surface expression of tissue-residency markers indicate that breastmilk T cells represented tissue-adapted rather than circulatory T cells. In addition, breastmilk T cells had a broad homing profile and higher activation markers in these migratory subsets. The partly overlapping transcriptome profile between breastmilk and breast tissue T cells, particularly cytotoxic T cells, might support a role in local immune defense in the mammary gland. However, unique features of breastmilk, such as Tregs, might imply an additional role in neonatal immune support. We found some correlations between the breastmilk T cell profile and clinical parameters, most notably with maternal and household factors. Together, our data suggest that breastmilk contains an adapted T cell population that exerts their function in specific tissue sites.

Background: In patients with asthma, respiratory syncytial virus (RSV) infections can cause disease exacerbation by infecting the epithelial layer of the airways, inducing subsequent immune response. The type I interferon antiviral response of epithelial cells upon RSV infection is found to be reduced in asthma in most-but not all-studies. Moreover, the molecular mechanisms causing the differences in the asthmatic bronchial epithelium in response to viral infection are poorly understood., Methods: Here, we investigated the transcriptional response to RSV infection of primary bronchial epithelial cells (pBECs) from patients with asthma (n=8) and healthy donors (n=8). The pBECs obtained from bronchial brushes were differentiated in air-liquid interface conditions and infected with RSV. After 3 days, cells were processed for single-cell RNA sequencing., Results: A strong antiviral response to RSV was observed for all cell types, for all samples (p<1e-48). Most (1045) differentially regulated genes following RSV infection were found in cells transitioning to secretory cells. Goblet cells from patients with asthma showed lower expression of genes involved in the interferon response (false discovery rate <0.05), including OASL , ICAM1 and TNFAIP3 . In multiciliated cells, an impairment of the signalling pathways involved in the response to RSV in asthma was observed., Conclusion: Our results highlight that the response to RSV infection of the bronchial epithelium in asthma and healthy airways was largely similar. However, in asthma, the response of goblet and multiciliated cells is impaired, highlighting the need for studying airway epithelial cells at high resolution in the context of asthma exacerbation., Competing Interests: Competing interests: GHK, MCN and MvdB received project funding from GlaxoSmithKline. GHK and MvdB received funding from AstraZeneca. MvdB received funding from Novartis, Genentech and Roche., (© Author(s) (or their employer(s)) 2024. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Objectives: Children are generally considered main drivers of transmission for respiratory viruses, but the emergence of SARS-CoV-2 challenged this paradigm. Human rhinovirus (RV) continued to co-circulate throughout the pandemic, allowing for direct comparison of age-specific infectivity and susceptibility within households between these viruses during a time of low SARS-CoV-2 population immunity., Methods: Households with children were prospectively monitored for ≥23 weeks between August 2020 and July 2021. Upon onset of respiratory symptoms in a household, an outbreak study was initiated, including questionnaires and repeated nasal self-sampling in all household members. Swabs were tested by PCR. Age-stratified within-household secondary attack rates (SARs) were compared between SARS-CoV-2 and RV., Results: A total of 307 households participated, including 582 children and 627 adults. Overall, SAR was lower for SARS-CoV-2 than for RV (aOR 0.55) and age distributions differed between both viruses (p < 0.001). Following household exposure, children were significantly less likely to become infected with SARS-CoV-2 compared to RV (aOR 0.16), whereas this was opposite in adults (aOR 1.71)., Conclusion: In households, age-specific susceptibility to SARS-CoV-2 and RV differs and drives differences in household transmission between these pathogens. This highlights the importance of characterizing age-specific transmission risks, particularly for emerging infections, to guide appropriate infection control interventions., Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Dr. Bont has regular interaction with pharmaceutical and other industrial partners. He has not received personal fees or other personal benefits. UMCU has received major funding (>€100,000 per industrial partner) for investigator-initiated studies from AbbVie, MedImmune, AstraZeneca, Sanofi, Janssen, Pfizer, MSD and MeMed Diagnostics. UMCU has received major funding for the RSV GOLD study from the Bill and Melinda Gates Foundation. UMCU has received major funding as part of the public–private partnership IMI-funded RESCEU and PROMISE projects with partners GSK, Novavax, Janssen, AstraZeneca, Pfizer and Sanofi. UMCU has received major funding by Julius Clinical for participating in clinical studies sponsored by MedImmune and Pfizer. UMCU received minor funding (€1000–25,000 per industrial partner) for consultation and invited lectures by AbbVie, MedImmune, Ablynx, Bavaria Nordic, MabXience, GSK, Novavax, Pfizer, Moderna, AstraZeneca, MSD, Sanofi, Janssen. Dr. Bont is the founding chairman of the ReSViNET Foundation. All other authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Background: The key correlate of protection of respiratory syncytial virus (RSV) vaccines and monoclonal antibodies (mAbs) is virus neutralization, measured via sera obtained through venipuncture. Dried blood obtained with a finger prick can simplify acquisition, processing, storage, and transport in trials and thereby reduce costs. In this study, we validate an assay to measure RSV neutralization in dried capillary blood., Methods: Functional antibodies were compared between matched serum and dried blood samples from a phase 1 trial with RSM01, an investigational anti-RSV prefusion F mAb. Hep-2 cells were infected with a serial dilution of sample-virus mixture by using RSV-A2-mKate to determine the half-maximal inhibitory concentration. Stability of dried blood was evaluated over time and during temperature stress., Results: Functional antibodies in dried blood were highly correlated with serum (R2 = 0.98, P < .0001). The precision of the assay for dried blood was similar to serum. The function of mAb remained stable for 9 months at room temperature and frozen dried blood samples., Conclusions: We demonstrated the feasibility of measuring RSV neutralization using dried blood as a patient-centered solution that may replace serology testing in trials against RSV or other viruses, such as influenza and SARS-CoV-2. Clinical Trials Registration.  NCT05118386 (ClinicalTrials.gov)., Competing Interests: Potential conflicts of interest. University Medical Center Utrecht (UMCU) has received major funding (>€100 000 per industrial partner) for investigator-initiated studies from AbbVie, MedImmune, AstraZeneca, Sanofi, Janssen, Pfizer, MSD, MeMed Diagnostics, the Bill and Melinda Gates Foundation, Bill & Melinda Gates Medical Research Institute, and the Dutch Lung Foundation. UMCU has received major funding as part of the public-private partnership Innovative Medicines Initiative–funded RESCEU and PROMISE projects with partners GSK, Novavax, Janssen, AstraZeneca, Pfizer, and Sanofi. UMCU has received major funding by Julius Clinical for participating in clinical studies sponsored by MedImmune and Pfizer. UMCU received minor funding (€1000–€25 000 per industrial partner) for consultation and invited lectures by AbbVie, MedImmune, Ablynx, Bavaria Nordic, MabXience, GSK, Novavax, Pfizer, Moderna, Astrazeneca, MSD, Sanofi, and Janssen. L. J. B. and N. I. M. have regular interaction with pharmaceutical and other industrial partners. They have not received personal fees or other personal benefits. L. J. B. is the founding chair of the ReSViNET Foundation. J. T. W. is an employee at the Bill & Melinda Gates Medical Research Institute. A. D.-C. and T. J. R. are supported by funding from the Intramural Research Program of the NIAID. All other authors report no potential conflicts. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed., (© The Author(s) 2023. Published by Oxford University Press on behalf of Infectious Diseases Society of America.)

Objective: Non-disease-specific WHO-CHOICE unit costs are often used in cost and cost-effectiveness studies in the absence of country-specific data. This study aims to compare reported country-specific disease costs and the corresponding WHO-CHOICE estimates. We use generically defined "diarrhea" (including rotavirus diarrhea) and pathogen-specific "respiratory syncytial virus (RSV)" disease as examples., Methods: We updated systematic reviews for both diseases in low-income (LICs), lower-middle-income (LMICs) and upper-middle-income (UMICs) countries. Diarrheal (including a sub-analysis of rotavirus-specific) and RSV-specific outpatient and inpatient costs per episode were extracted and compared with WHO-CHOICE estimates in the same countries. If a consistent pattern of under- or over-estimation was identified, we quantified the magnitude of the discrepancy. All costs were updated to 2022 international dollar values., Results: Out of 1975 new records identified, 23 new cost studies were included. Including previous reviews, we retained 31 diarrhea and 16 RSV studies for comparison. WHO-CHOICE based direct medical costs were similar for diarrheal disease including rotavirus diarrhea, but lower for RSV-related disease. We estimated the cost per episode of diarrhea and RSV in 128 countries. RSV outpatient cost were adjusted by multiplying WHO-CHOICE costs by 6.89 (95% uncertainty interval: 5.58-8.58) in LICs and LMICs and 5.87 (4.95-6.96) in UMICs; RSV inpatient costs were multiplied by 1.43 (1.01-2.01) and 1.36 (0.82-2.27), respectively., Conclusion: WHO-CHOICE based costs should be used cautiously. They aligned well with studies for diarrheal disease, but underestimate costs of RSV-related disease. More country- and disease-specific cost data are needed, especially for RSV in LICs., Competing Interests: Competing interests VEP was previously a member of the WHO Immunization and Vaccine-related Implementation Research Advisory Committee (IVIR-AC). Outside the submitted work, PB and LB reports grants from RESCEU and PROMISE, Innovative Medicines Initiative 2 of the European Commission, but they have not received any personal fees or other personal benefits. LB is the founding chairman of the ReSViNET Foundation. He also declares that he has regular interaction with pharmaceutical and other industrial partners. He has not received personal fees or other personal benefits. Outside the submitted work, his institute UMCU has received major funding (>€100,000 per industrial partner) for investigator-initiated studies from AstraZeneca, Sanofi, Janssen, Pfizer, MSD and MeMed Diagnostics. UMCU has received major funding from the Bill and Melinda Gates Foundation. UMCU has received major funding by Julius Clinical for participating in clinical studies sponsored by AstraZeneca, Merck and Pfizer. UMCU received minor funding (€1,000–25,000 per industrial partner) for consultation, DSMB membership or invited lectures by Ablynx, Bavaria Nordic, GSK, Novavax, Pfizer, Moderna, AstraZeneca, MSD, Sanofi, Janssen. Other authors declared no competing interests.

Down syndrome (DS) is characterized by lowered immune competence and premature aging. We previously showed decreased antibody response following SARS-CoV-2 vaccination in adults with DS. IgG1 Fc glycosylation patterns are known to affect the effector function of IgG and are associated with aging. Here, we compare total and anti-spike (S) IgG1 glycosylation patterns following SARS-CoV-2 vaccination in DS and healthy controls (HC). Total and anti-Spike IgG1 Fc N-glycan glycoprofiles were measured in non-exposed adults with DS and controls before and after SARS-CoV-2 vaccination by liquid chromatography-mass spectrometry (LC-MS) of Fc glycopeptides. We recruited N = 44 patients and N = 40 controls. We confirmed IgG glycosylation patterns associated with aging in HC and showed premature aging in DS. In DS, we found decreased galactosylation (50.2% vs. 59.0%) and sialylation (6.7% vs. 8.5%) as well as increased fucosylation (97.0% vs. 94.6%) of total IgG. Both cohorts showed similar bisecting GlcNAc of total and anti-S IgG1 with age. In contrast, anti-S IgG1 of DS and HC showed highly comparable glycosylation profiles 28 days post vaccination. The IgG1 glycoprofile in DS exhibits strong premature aging. The combination of an early decrease in IgG1 Fc galactosylation and sialylation and increase in fucosylation is predicted to reduce complement activity and decrease FcγRIII binding and subsequent activation, respectively. The altered glycosylation patterns, combined with decreased antibody concentrations, help us understand the susceptibility to severe infections in DS. The effect of premature aging highlights the need for individuals with DS to receive tailored vaccines and/or vaccination schedules., (© 2024 The Authors. Aging Cell published by Anatomical Society and John Wiley & Sons Ltd.)

Background: The implementation of the approved respiratory syncytial virus (RSV) preventive interventions in immunisation programmes is advancing rapidly. Insight into healthcare costs of RSV-related paediatric intensive care unit (PICU) admissions is lacking, but of great importance to evaluate the impact of implementation. Therefore, this study aimed to determine the total annual RSV-related paediatric intensive care healthcare costs in the Netherlands., Methods: A nationwide prospective, observational, multicenter study was performed from September 2021 until June 2023. The total annual RSV-related healthcare costs on PICUs in the Netherlands were calculated using RSV-related costs (subgroup I) and consequential costs (subgroup II and III). Subgroup I comprised all PICU admitted infants ≤12 months of age with laboratory-confirmed RSV infection. Subgroup II and III consisted of postponed elective PICU admissions and refused acute PICU admissions due to RSV-related lack of PICU capacity., Findings: A total of 424 infants with RSV-related PICU admission were included. Median age at PICU admission was 46 days (IQR 25-89). The median length of PICU admission was 5 days (IQR 3-8). The total RSV-related PICU costs are € 3,826,386 in 2021-2022, and € 3,183,888 in 2022-2023. Potential costs averted by RSV preventive interventions is € 1.9 to € 2.6 million depending on season, and the duration of protection., Interpretation: RSV-related PICU admissions cost €3.1 to €3.8 million in the Netherlands during one season. The introduction of new RSV preventive interventions into the Dutch immunisation programme will generate significant cost-savings on PICUs and decreases the admission burden of PICUs., Funding: None., Competing Interests: EP, CB, MH, MK, SM, AN, MR, RWA, JvW and GF have no competing interests to declare. LB has regular interaction with pharmaceutical and other industrial partners. He has not received personal fees or other personal benefits. UMCU has received major funding (>€100,000 per industrial partner) for investigator initiated studies from AstraZeneca, Sanofi, Janssen, Pfizer, MSD and MeMed Diagnostics. UMCU has received major funding from the Bill and Melinda Gates Foundation. UMCU has received major funding as part of the public private partnership IMI-funded RESCEU and PROMISE projects with partners GSK, Novavax, Janssen, AstraZeneca, Pfizer and Sanofi. UMCU has received major funding by Julius Clinical for participating in clinical studies sponsored by AstraZeneca, Merck and Pfizer. UMCU received minor funding (€1000–25,000 per industrial partner) for consultation, DSMB membership or invited lectures by Ablynx, Bavaria Nordic, GSK, Novavax, Pfizer, Moderna, Astrazeneca, MSD, Sanofi, Janssen. LB is the founding chairman of the ReSViNET Foundation. JGW has been an investigator for clinical trials sponsored by pharmaceutical companies including AstraZeneca, Merck, Pfizer, Sanofi, and Janssen and an investigator for clinical trials funded by IMI/Horizon2020 and ZonMw. All funds have been paid to the institution (UMCU). JGW participated in advisory boards of Janssen and Sanofi and was a speaker at a Sanofi sponsored symposium with fees paid to the institution (UMCU)., (© 2024 The Author(s).)

Background: Respiratory syncytial virus (RSV) is a major cause of lower respiratory tract infections (LRTIs) in infants. Maternal RSV vaccination is a preventive strategy of great interest, as it could have a substantial impact on infant RSV disease burden. In recent years, the clinical development of maternal RSV vaccines has advanced rapidly., Objectives: To assess the efficacy and safety of maternal respiratory syncytial virus (RSV) vaccination for preventing RSV disease in infants., Search Methods: We searched Cochrane Pregnancy and Childbirth's Trials Register and two other trials registries on 21 October 2022. We updated the search on 27 July 2023, when we searched MEDLINE, Embase, CENTRAL, CINAHL, and two trials registries. Additionally, we searched the reference lists of retrieved studies and conference proceedings. There were no language restrictions on our searches., Selection Criteria: We included randomised controlled trials (RCTs) comparing maternal RSV vaccination with placebo or no intervention in pregnant women of any age. The primary outcomes were hospitalisation with clinically confirmed or laboratory-confirmed RSV disease in infants. The secondary outcomes covered adverse pregnancy outcomes (intrauterine growth restriction, stillbirth, and maternal death) and adverse infant outcomes (preterm birth, congenital abnormalities, and infant death)., Data Collection and Analysis: We used standard Cochrane methods and assessed the certainty of evidence using the GRADE approach., Main Results: We included six RCTs (25 study reports) involving 17,991 pregnant women. The intervention was an RSV pre-F protein vaccine in four studies, and an RSV F protein nanoparticle vaccine in two studies. In all studies, the comparator was a placebo (saline, formulation buffer, or sterile water). We judged four studies at overall low risk of bias and two studies at overall high risk (mainly due to selection bias). All studies were funded by pharmaceutical companies. Maternal RSV vaccination compared with placebo reduces infant hospitalisation with laboratory-confirmed RSV disease (risk ratio (RR) 0.50, 95% confidence interval (CI) 0.31 to 0.82; 4 RCTs, 12,216 infants; high-certainty evidence). Based on an absolute risk with placebo of 22 hospitalisations per 1000 infants, our results represent 11 fewer hospitalisations per 1000 infants from vaccinated pregnant women (15 fewer to 4 fewer). No studies reported infant hospitalisation with clinically confirmed RSV disease. Maternal RSV vaccination compared with placebo has little or no effect on the risk of congenital abnormalities (RR 0.96, 95% CI 0.88 to 1.04; 140 per 1000 with placebo, 5 fewer per 1000 with RSV vaccination (17 fewer to 6 more); 4 RCTs, 12,304 infants; high-certainty evidence). Maternal RSV vaccination likely has little or no effect on the risk of intrauterine growth restriction (RR 1.32, 95% CI 0.75 to 2.33; 3 per 1000 with placebo, 1 more per 1000 with RSV vaccination (1 fewer to 4 more); 4 RCTs, 12,545 pregnant women; moderate-certainty evidence). Maternal RSV vaccination may have little or no effect on the risk of stillbirth (RR 0.81, 95% CI 0.38 to 1.72; 3 per 1000 with placebo, no difference with RSV vaccination (2 fewer to 3 more); 5 RCTs, 12,652 pregnant women). There may be a safety signal warranting further investigation related to preterm birth. This outcome may be more likely with maternal RSV vaccination, although the 95% CI includes no effect, and the evidence is very uncertain (RR 1.16, 95% CI 0.99 to 1.36; 6 RCTs, 17,560 infants; very low-certainty evidence). Based on an absolute risk of 51 preterm births per 1000 infants from pregnant women who received placebo, there may be 8 more per 1000 infants from pregnant women with RSV vaccination (1 fewer to 18 more). There was one maternal death in the RSV vaccination group and none in the placebo group. Our meta-analysis suggests that RSV vaccination compared with placebo may have little or no effect on the risk of maternal death (RR 3.00, 95% CI 0.12 to 73.50; 3 RCTs, 7977 pregnant women; low-certainty evidence). The effect of maternal RSV vaccination on the risk of infant death is very uncertain (RR 0.81, 95% CI 0.36 to 1.81; 6 RCTs, 17,589 infants; very low-certainty evidence)., Authors' Conclusions: The findings of this review suggest that maternal RSV vaccination reduces laboratory-confirmed RSV hospitalisations in infants. There are no safety concerns about intrauterine growth restriction and congenital abnormalities. We must be careful in drawing conclusions about other safety outcomes owing to the low and very low certainty of the evidence. The evidence available to date suggests RSV vaccination may have little or no effect on stillbirth, maternal death, and infant death (although the evidence for infant death is very uncertain). However, there may be a safety signal warranting further investigation related to preterm birth. This is driven by data from one trial, which is not fully published yet. The evidence base would be much improved by more RCTs with substantial sample sizes and well-designed observational studies with long-term follow-up for assessment of safety outcomes. Future studies should aim to use standard outcome measures, collect data on concomitant vaccines, and stratify data by timing of vaccination, gestational age at birth, race, and geographical setting., (Copyright © 2024 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.)

Respiratory syncytial virus (RSV) is a leading cause of acute lower respiratory tract infection in young children and the second leading cause of infant death worldwide. While global circulation has been extensively studied for respiratory viruses such as seasonal influenza, and more recently also in great detail for SARS-CoV-2, a lack of global multi-annual sampling of complete RSV genomes limits our understanding of RSV molecular epidemiology. Here, we capitalise on the genomic surveillance by the INFORM-RSV study and apply phylodynamic approaches to uncover how selection and neutral epidemiological processes shape RSV diversity. Using complete viral genome sequences, we show similar patterns of site-specific diversifying selection among RSVA and RSVB and recover the imprint of non-neutral epidemic processes on their genealogies. Using a phylogeographic approach, we provide evidence for air travel governing the global patterns of RSVA and RSVB spread, which results in a considerable degree of phylogenetic mixing across countries. Our findings highlight the potential of systematic global RSV genomic surveillance for transforming our understanding of global RSV spread., (© 2024. The Author(s).)

A novel host-protein score (called MMBV) helps to distinguish bacterial from viral infection by combining the blood concentrations of three biomarkers: tumour necrosis factor related apoptosis inducing ligand (TRAIL), interferon gamma induced protein 10 (IP-10), and C-reactive protein (CRP). These host biomarkers are differentially expressed in response to bacterial versus viral acute infection. We conducted a prospective study, with a time series design, in healthy adult volunteers in the Netherlands. The aim was to determine the variability of TRAIL, IP-10, and CRP and the MMBV score in healthy adults across time. Up to six blood samples were taken from each healthy volunteer over a period of up to four weeks. In 77 healthy participants without recent or current symptoms, MMBV scores (maximal) were bacterial in 1.3 % and viral (or other non-infectious etiology) in 93.5 % of participants. There was little variation in the mean concentrations of TRAIL (74.5 pg/ml), IP-10 (113.6 pg/ml), and CRP (1.90 mg/L) as well as the MMBV score. The variability of biomarker measurement was comparable to the precision of the measurement platform for TRAIL, IP-10, and CRP. Our findings establish the mean values of these biomarkers and MMBV in healthy individuals and indicate little variability between and within individuals over time, supporting the potential utility of this novel diagnostic to detect infection-induced changes., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Background: The COVID-19 pandemic is reported to have affected the epidemiology of respiratory syncytial virus (RSV), which could have important implications for RSV prevention and control strategies. We aimed to assess the hospitalisation burden of RSV-associated acute lower respiratory infection (ALRI) in children younger than 5 years during the pandemic period and the possible changes in RSV epidemiology from a global perspective., Methods: We conducted a systematic literature search for studies published between Jan 1, 2020, and June 30, 2022, in MEDLINE, Embase, Global Health, Web of Science, the WHO COVID-19 Research Database, CINAHL, LILACS, OpenGrey, CNKI, WanFang, and CqVip. We included unpublished data on RSV epidemiology shared by international collaborators. Eligible studies reported data on at least one of the following measures for children (aged <5 years) hospitalised with RSV-associated ALRI: hospital admission rates, in-hospital case fatality ratio, and the proportion of hospitalised children requiring supplemental oxygen or requiring mechanical ventilation or admission to intensive care. We used a generalised linear mixed-effects model for data synthesis to measure the changes in the incidence, age distribution, and disease severity of children hospitalised with RSV-associated ALRI during the pandemic, compared with the year 2019., Findings: We included 61 studies from 19 countries, of which 14 (23%) studies were from the published literature (4052 identified records) and 47 (77%) were from unpublished datasets. Most (51 [84%]) studies were from high-income countries; nine (15%) were from upper-middle-income countries, one (2%) was from a lower-middle-income country (Kenya), and none were from a low-income country. 15 studies contributed to the estimates of hospitalisation rate and 57 studies contributed to the severity analyses. Compared with 2019, the rates of RSV-associated ALRI hospitalisation in all children (aged 0-60 months) in 2020 decreased by 79·7% (325 000 cases vs 66 000 cases) in high-income countries, 13·8% (581 000 cases vs 501 000 cases) in upper-middle-income countries, and 42·3% (1 378 000 cases vs 795 000 cases) in Kenya. In high-income countries, annualised rates started to rise in 2021, and by March, 2022, had returned to a level similar to 2019 (6·0 cases per 1000 children [95% uncertainty interval 5·4-6·8] in April, 2021, to March, 2022, vs 5·0 cases per 1000 children [3·6-6·8] in 2019). By contrast, in middle-income countries, rates remained lower in the latest period with data available than in 2019 (for upper-middle-income countries, 2·1 cases [0·7-6·1] in April, 2021, to March, 2022, vs 3·4 [1·2-9·7] in 2019; for Kenya, 2·2 cases [1·8-2·7] in 2021 vs 4·1 [3·5-4·7] in 2019). Across all time periods and income regions, hospitalisation rates peaked in younger infants (aged 0 to <3 months) and decreased with increasing age. A significantly higher proportion of children aged 12-24 months were hospitalised with RSV-associated ALRI in high-income and upper-middle-income countries during the pandemic years than in 2019, with odds ratios ranging from 1·30 (95% uncertainty interval 1·07-1·59) to 2·05 (1·66-2·54). No consistent changes in disease severity were observed., Interpretation: The hospitalisation burden of RSV-associated ALRI in children younger than 5 years was significantly reduced during the first year of the COVID-19 pandemic. The rebound in hospitalisation rates to pre-pandemic rates observed in the high-income region but not in the middle-income region by March, 2022, suggests a persistent negative impact of the pandemic on health-care systems and health-care access in the middle-income region. RSV surveillance needs to be established (or re-established) to monitor changes in RSV epidemiology, particularly in low-income and lower-middle-income countries., Funding: EU Innovative Medicines Initiative Preparing for RSV Immunisation and Surveillance in Europe (PROMISE), Bill & Melinda Gates Foundation, and WHO., Competing Interests: Declaration of interests UK is a current employee of Pfizer but took part in this project as a postgraduate student at the University of Edinburgh. NW has received grant funding from the Bill & Melinda Gates Foundation, Sanofi, and US Centers for Disease Control and Prevention. CFY reports grants from the National Medical Research Council Singapore and the Wellcome Trust, and fees from Sanofi, Pfizer, and Takeda, outside of the submitted work. HN reports grants from the Innovative Medicines Initiative related to the submitted work, and grants from WHO, the National Institute for Health Research, Pfizer, and Icosavax, and personal fees from the Bill & Melinda Gates Foundation, Pfizer, ReViral, GlaxoSmithKline, Merck, Icosavax, Sanofi, Novavax, and AbbVie, outside of the submitted work. YL reports grants from WHO, the Wellcome Trust, and GlaxoSmithKline, and personal fees from Pfizer, outside of the submitted work. All other authors declare no competing interests., (© 2024 World Health Organization. Published by Elsevier Ltd. All rights reserved. This is an Open Access article published under the CC BY 3.0 IGO license which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. In any use of this article, there should be no suggestion that WHO endorses any specific organisation, products or services. The use of the WHO logo is not permitted. This notice should be preserved along with the article's original URL.)

Purpose of Review: With interventions to prevent respiratory syncytial virus (RSV) infection within reach, this review aims to provide healthcare professionals with the latest information necessary to inform parents and assess the potential impact of RSV prevention on everyday practice. We address frequently asked questions for parental counseling., Recent Findings: Numerous studies emphasize the major burden of RSV on young children, parents, healthcare and society. In the first year of life, about 14% of healthy term infants visit a doctor and 2% require hospitalization due to RSV. In older children (1--5 years), RSV infections and associated morbidity (wheeze, acute otitis media) are major drivers of outpatient visits. A novel maternal RSV vaccine and long-acting mAb can provide protection during infants' first months of life. This maternal vaccine showed 70.9% efficacy against severe RSV infection within 150 days after birth; the mAb nirsevimab reduces medically attended RSV infections by 79.5% within 150 days after administration. Both gained regulatory approval in the USA (FDA) and Europe (EMA)., Summary: Novel RSV immunizations hold promise to reduce the RSV burden in infants, with substantial impact on everyday practice. Tailored parental guidance will be instrumental for successful implementation. Awaiting pediatric vaccines, RSV infections beyond infancy will still pose a significant outpatient burden., (Copyright © 2023 The Author(s). Published by Wolters Kluwer Health, Inc.)

Background: Infants and young children born prematurely are at high risk of severe acute lower respiratory infection (ALRI) caused by respiratory syncytial virus (RSV). In this study, we aimed to assess the global disease burden of and risk factors for RSV-associated ALRI in infants and young children born before 37 weeks of gestation., Methods: We conducted a systematic review and meta-analysis of aggregated data from studies published between Jan 1, 1995, and Dec 31, 2021, identified from MEDLINE, Embase, and Global Health, and individual participant data shared by the Respiratory Virus Global Epidemiology Network on respiratory infectious diseases. We estimated RSV-associated ALRI incidence in community, hospital admission, in-hospital mortality, and overall mortality among children younger than 2 years born prematurely. We conducted two-stage random-effects meta-regression analyses accounting for chronological age groups, gestational age bands (early preterm, <32 weeks gestational age [wGA], and late preterm, 32 to <37 wGA), and changes over 5-year intervals from 2000 to 2019. Using individual participant data, we assessed perinatal, sociodemographic, and household factors, and underlying medical conditions for RSV-associated ALRI incidence, hospital admission, and three severity outcome groups (longer hospital stay [>4 days], use of supplemental oxygen and mechanical ventilation, or intensive care unit admission) by estimating pooled odds ratios (ORs) through a two-stage meta-analysis (multivariate logistic regression and random-effects meta-analysis). This study is registered with PROSPERO, CRD42021269742., Findings: We included 47 studies from the literature and 17 studies with individual participant-level data contributed by the participating investigators. We estimated that, in 2019, 1 650 000 (95% uncertainty range [UR] 1 350 000-1 990 000) RSV-associated ALRI episodes, 533 000 (385 000-730 000) RSV-associated hospital admissions, 3050 (1080-8620) RSV-associated in-hospital deaths, and 26 760 (11 190-46 240) RSV-attributable deaths occurred in preterm infants worldwide. Among early preterm infants, the RSV-associated ALRI incidence rate and hospitalisation rate were significantly higher (rate ratio [RR] ranging from 1·69 to 3·87 across different age groups and outcomes) than for all infants born at any gestational age. In the second year of life, early preterm infants and young children had a similar incidence rate but still a significantly higher hospitalisation rate (RR 2·26 [95% UR 1·27-3·98]) compared with all infants and young children. Although late preterm infants had RSV-associated ALRI incidence rates similar to that of all infants younger than 1 year, they had higher RSV-associated ALRI hospitalisation rate in the first 6 months (RR 1·93 [1·11-3·26]). Overall, preterm infants accounted for 25% (95% UR 16-37) of RSV-associated ALRI hospitalisations in all infants of any gestational age. RSV-associated ALRI in-hospital case fatality ratio in preterm infants was similar to all infants. The factors identified to be associated with RSV-associated ALRI incidence were mainly perinatal and sociodemographic characteristics, and factors associated with severe outcomes from infection were mainly underlying medical conditions including congenital heart disease, tracheostomy, bronchopulmonary dysplasia, chronic lung disease, or Down syndrome (with ORs ranging from 1·40 to 4·23)., Interpretation: Preterm infants face a disproportionately high burden of RSV-associated disease, accounting for 25% of RSV hospitalisation burden. Early preterm infants have a substantial RSV hospitalisation burden persisting into the second year of life. Preventive products for RSV can have a substantial public health impact by preventing RSV-associated ALRI and severe outcomes from infection in preterm infants., Funding: EU Innovative Medicines Initiative Respiratory Syncytial Virus Consortium in Europe., Competing Interests: Declaration of interests YM and ES were affiliated with the University of Edinburgh when this work was conducted. YM is currently affiliated to the School of Public Health, Wuhan University, Wuhan, China and ES is employed by University College Hospital, University College Hospitals NHS Foundation Trust, London, UK. XW reports grants from GSK to their institution and personal fees from Pfizer, outside the submitted work. YL reports grants from Wellcome Trust, WHO, and GSK paid to their institution, and personal fees from Pfizer, outside the submitted work. TS reports grants from Royal Society of Edinburgh outside the submitted work. LJB reports regular interactions with AbbVie, MedImmune, Ablynx, Bavaria Nordic, MabXience, GSK, Novavax, Pfizer, Moderna, AstraZeneca, MSD, Sanofi, Genzyme, MeMed Diagnostics, and Janssen but has not received personal fees or other personal benefits; being the founding chairman of the ReSViNET Foundation; their affiliation (University Medical Centre Utrecht) has received major funding (>€100 000 per industrial partner) for investigator-initiated studies from AbbVie, MedImmune, AstraZeneca, Sanofi, Janssen, Pfizer, MSD, and MeMed Diagnostics; major funding for the RSV GOLD study from the Bill & Melinda Gates Foundation; major funding as part of the public private partnership IMI-funded RESCEU and PROMISE projects with partners GSK, Novavax, Janssen, AstraZeneca, Pfizer, and Sanofi; major funding by Julius Clinical for participating in clinical studies sponsored by MedImmune and Pfizer; and minor funding (€1000–€25 000 per industrial partner) for consultation and invited lectures by AbbVie, MedImmune, Ablynx, Bavaria Nordic, MabXience, GSK, Novavax, Pfizer, Moderna, AstraZeneca, MSD, Sanofi, and Janssen. HYC reports consulting for Ellume, Pfizer, and the Gates Foundation; serving on advisory boards for Vir, Merck, and AbbVie; conducting continuing medical education teaching with Medscape, Vindico, Cataylst CME, and Clinical Care Options; research funding from Gates Ventures; and receiving support and reagents from Ellume and Cepheid, all outside of the submitted work. HJZ reports grants from the Gates Foundation, AstraZeneca, MSD, and Pfizer paid to their institution outside the submitted work, and serving on advisory boards for MSD. TH reports personal fees from Janssen, Sanofi, Enanta, MSD, and Moderna, all outside of the submitted work. MHJ reports personal fees from AstraZeneca, OM-Pharma, Chiesi, GSK, and Boehringer Ingelheim, outside the submitted work. MCN reports grants from the Gates Foundation, European & Developing Countries Clinical Trials Partnership, Pfizer, AstraZeneca, and Sanofi; and serving on advisory boards for Sanofi, all outside the submitted work. BR received honoraria due to lectures from AbbVie, Germania, Sanofi, AstraZeneca, Milupa, Nestle, and Fresenius, outside the submitted work; and travel support from AbbVie, Chiesi, AstraZeneca, Sanofi, and Nestle. HN reports grants from the Innovative Medicines Initiative related to the submitted work; grants from WHO, the National Institute for Health Research, Pfizer, and Icosavax; and personal fees from the Gates Foundation, Pfizer, ReViral, GSK, Merck, Icosavax, Sanofi, Novavax, and AbbVie, outside the submitted work. CFY reports grants from National Medical Research Council Singapore and Wellcome Trust, and funding to attend conferences and honorarium from Sanofi, Pfizer, and Takeda, outside the submitted work. All other authors declare no competing interests., (Copyright © 2024 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 license. Published by Elsevier Ltd.. All rights reserved.)

Respiratory syncytial virus (RSV) is the leading cause of hospitalisation for respiratory infection in young children. RSV disease severity is known to be age-dependent and highest in young infants, but other correlates of severity, particularly the presence of additional respiratory pathogens, are less well understood. In this study, nasopharyngeal swabs were collected from two cohorts of RSV-positive infants <12 months in Spain, the UK, and the Netherlands during 2017-20. We show, using targeted metagenomic sequencing of >100 pathogens, including all common respiratory viruses and bacteria, from samples collected from 433 infants, that burden of additional viruses is common (111/433, 26%) but only modestly correlates with RSV disease severity. In contrast, there is strong evidence in both cohorts and across age groups that presence of Haemophilus bacteria (194/433, 45%) is associated with higher severity, including much higher rates of hospitalisation (odds ratio 4.25, 95% CI 2.03-9.31). There is no evidence for association between higher severity and other detected bacteria, and no difference in severity between RSV genotypes. Our findings reveal the genomic diversity of additional pathogens during RSV infection in infants, and provide an evidence base for future causal investigations of the impact of co-infection on RSV disease severity., (© 2024. The Author(s).)

Background: Respiratory syncytial virus (RSV) is a significant cause of infant morbidity and mortality worldwide. Most children experience at least one 1 RSV infection by the age of two 2 years, but not all develop severe disease. However, the understanding of genetic risk factors for severe RSV is incomplete. Consequently, we conducted a genome-wide association study of RSV severity., Methods: Disease severity was assessed by the ReSVinet scale, in a cohort of 251 infants aged 1 week to 1 year. Genotyping data were collected from multiple European study sites as part of the RESCEU Consortium. Linear regression models were used to assess the impact of genotype on RSV severity and gene expression as measured by microarray., Results: While no SNPs reached the genome-wide statistical significance threshold (P < 5 × 10-8), we identified 816 candidate SNPs with a P-value of <1 × 10-4. Functional annotation of candidate SNPs highlighted genes relevant to neutrophil trafficking and cytoskeletal functions, including LSP1 and RAB27A. Moreover, SNPs within the RAB27A locus significantly altered gene expression (false discovery rate, FDR P < .05)., Conclusions: These findings may provide insights into genetic mechanisms driving severe RSV infection, offering biologically relevant information for future investigations., Competing Interests: Potential conflicts of interest. F. M.-T. and P. J. M. O. have received honoraria from the GSK group of companies, Pfizer, Sanofi Pasteur, MSD, Seqirus, AstraZeneca, Moderna, and Janssen for taking part in advisory boards and expert meetings and for acting as a speaker in congresses outside the scope of the submitted work. F. M.-T. has also acted as principal investigator in randomized controlled trials of the aforementioned companies as well as Ablynx, Gilead, Regeneron, Roche, Abbott, Novavax, and MedImmune, with honoraria paid to his institution. S. B. D. has received honoraria from MSD and Sanofi for taking part in RSV advisory boards and has provided consultancy and/or investigator roles in relation to product development for Janssen, AstraZeneca, Pfizer, Moderna, Valneva, MSD, iLiAD, and Sanofi with fees paid to St George's, University of London. S. B. D. is a member of the UK Department of Health and Social Care's Joint Committee on Vaccination and Immunisation RSV subcommittee and Medicines and Healthcare Products Regulatory Agency's Paediatric Medicine Expert Advisory Group, but the reviews expressed herein do not necessarily represent any of those groups. A. J. P. is chair of the Department of Health and Social Care's Joint Committee on Vaccination and Immunisation. J. W. participated in the advisory board of Janssen and Sanofi with fees paid to University Medical Centre Utrecht and has been an investigator for clinical trials sponsored by pharmaceutical companies including AstraZeneca, Merck, Pfizer, Sanofi, and Janssen. All funds have been paid to University Medical Centre Utrecht. All other authors report no potential conflicts. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed., (© The Author(s) 2024. Published by Oxford University Press on behalf of Infectious Diseases Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Background: Respiratory syncytial virus (RSV) is a widespread respiratory pathogen, and RSV-related acute lower respiratory tract infections are the most common cause of respiratory hospitalization in children <2 years of age. Over the last 2 decades, a number of severity scores have been proposed to quantify disease severity for RSV in children, yet there remains no overall consensus on the most clinically useful score., Methods: We conducted a systematic review of English-language publications in peer-reviewed journals published since January 2000 assessing the validity of severity scores for children (≤24 months of age) with RSV and/or bronchiolitis, and identified the most promising scores. For included articles, (1) validity data were extracted, (2) quality of reporting was assessed using the Transparent Reporting of a multivariable prediction model for Individual Prognosis Or Diagnosis checklist (TRIPOD), and (3) quality was assessed using the Prediction Model Risk Of Bias Assessment Tool (PROBAST). To guide the assessment of the validity data, standardized cutoffs were employed, and an explicit definition of what we required to determine a score was sufficiently validated., Results: Our searches identified 8541 results, of which 1779 were excluded as duplicates. After title and abstract screening, 6670 references were excluded. Following full-text screening and snowballing, 32 articles, including 31 scores, were included. The most frequently assessed scores were the modified Tal score and the Wang Bronchiolitis Severity Score; none of the scores were found to be sufficiently validated according to our definition. The reporting and/or design of all the included studies was poor. The best validated score was the Bronchiolitis Score of Sant Joan de Déu, and a number of other promising scores were identified., Conclusions: No scores were found to be sufficiently validated. Further work is warranted to validate the existing scores, ideally in much larger datasets., Competing Interests: Potential conflicts of interest. Y. L. has received funding from the Wellcome Trust and GSK, outside the submitted work; and has received consulting fees from Pfizer. R. A. C. is an employee of the GSK group of companies, holds shares in the GSK group of companies, and has received other compensation from GSK, outside the submitted work; has received support from Westat (former employer) for attending meetings/travel; and has held stock or stock options from Westat. G. D. S. is an employee of the GSK group of companies and hold shares as part of his annual remunerations. L. B. has received funding through University Medical Center Utrecht from AbbVie, Janssen, the Bill & Melinda Gates Foundation, Nutricia Danon, MeMed Diagnostics, GSK, Novavax, AstraZeneca, Sanofi, Ablynx, Bavaria Nordic, MabXience, Novavax, and Pfizer. H. N. has received funding from the Innovative Medicines Initiative (IMI) (grant to institution), the National Institute for Health and Care Research, Icosavax, and Pfizer; has received consulting fees from the World Health Organization (WHO), Pfizer, the Bill & Melinda Gates Foundation, and Sanofi; has received honoraria from AbbVie for educational events; has received support for attending meetings/travel from Sanofi; and has served on a data and safety monitoring board or advisory board for GSK, Sanofi, Merck, WHO, Janssen, Novavax, ReSVinet, Icosavax, and Pfizer. Z. S. has received support for attending meetings/travel from PROMISE/IMI to attend the PROMISE AGM and 12th International RSV Symposium; and is a shareholder of Evidence-Based Health Care Ltd. E. P. reports no potential conflicts of interest. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed., (© The Author(s) 2023. Published by Oxford University Press on behalf of Infectious Diseases Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Background: During the first year of life, 1 in 4 infants develops a symptomatic respiratory syncytial virus (RSV) infection, yet only half seek medical attention. The current focus on medically attended RSV therefore underrepresents the true societal burden of RSV. We assessed the burden of nonmedically attended RSV infections and compared with medically attended RSV., Methods: We performed active RSV surveillance until the age of 1 year in a cohort (n = 993) nested within the Respiratory Syncytial Virus Consortium in EUrope (RESCEU) prospective birth cohort study enrolling healthy term-born infants in 5 European countries. Symptoms, medication use, wheezing, and impact on family life were analyzed., Results: For 97 of 120 (80.1%) nonmedically attended RSV episodes, sufficient data were available for analysis. In 50.5% (49/97), symptoms lasted ≥15 days. Parents reported impairment in usual daily activities in 59.8% (58/97) of episodes; worries, 75.3% (73/97); anxiety, 34.0% (33/97); and work absenteeism, 10.8% (10/93). Compared with medically attended RSV (n = 102, 9 hospital admissions), Respiratory Syncytial Virus NETwork (ReSViNET) severity scores were lower (3.5 vs 4.6, P < .001), whereas duration of respiratory symptoms and was comparable., Conclusions: Even when medical attendance is not required, RSV infection poses a substantial burden to infants, families, and society. These findings are important for policy makers when considering the implementation of RSV immunization. Clinical Trials Registration. ClinicalTrials.gov (NCT03627572)., Competing Interests: Potential conflicts of interest. M. A. v. H. has received honoraria for participation in advisory boards from Sanofi and Moderna and acted as a principal investigator in randomized clinical trials for Pfizer. T. H. has received honoraria for lectures or participation in advisory boards or data monitoring committees from Janssen, Sanofi, and MSD. A. J. P. is part of RESCEU (Respiratory Syncytial Virus Consortium in Europe), and his university received grant funding from the European Commission’s Innovative Medicines Initiative for this work. Oxford University has received grant funding from the Medical Research Council, Wellcome Trust, Bill & Melinda Gates Foundation, Serum Institute of India, and AstraZeneca. A. J. P. is a contributor to intellectual property licensed by Oxford University Innovation to AstraZeneca. A. J. P. is chair of the UK Joint Committtee of Vaccination and Immunisation and was a member of the World Health Organization’s Strategic Advisory Group of Experts on Immunization until 2022. S. C. provided clinical study advice or acted as principal investigator for GSK, Pfizer, MedImmune, Ablynx, Gilead, Ark Biosciences, Shionogi, and Janssen/Alios, with fees paid to the University of Edinburgh. F. M.-T. has received honoraria from GSK, Biofabri, Pfizer Inc, Sanofi Pasteur, MSD, Seqirus, and Janssen for taking part in advisory boards and expert meetings and for acting as a speaker in congresses outside the scope of the submitted work. F. M.-T. has also acted as principal investigator in randomized controlled trials of the aforementioned companies as well as Ablynx, Gilead, Regeneron, Roche, Abbott, Novavax, and MedImmune, with honoraria paid to his institution. A. D.-U. has been a subinvestigator for clinical trials sponsored by Pfizer and GSK and observational studies sponsored by Sanofi, with all funds paid to her institution. A. D.-U. has received funding for attending the Asociación Española Pediatría (Pediatric Spanish Association) meeting in 2022. L. J. B. has regular interaction with pharmaceutical and other industrial partners. He has not received personal fees or other personal benefits. University Medical Center Utrecht (UMCU) has received major funding (>€100 000 per industrial partner) for investigator-initiated studies from AbbVie, MedImmune, AstraZeneca, Sanofi, Janssen, Pfizer, MSD, and MeMed Diagnostics. UMCU has received major funding for the RSV GOLD study from the Bill & Melinda Gates Foundation. UMCU has received major funding as part of the public-private RESCEU and PROMISE projects, funded by the Innovative Medicines Initiative, in partnership with GSK, Novavax, Janssen, AstraZeneca, Pfizer, and Sanofi. UMCU has received major funding from Julius Clinical for participating in clinical studies sponsored by MedImmune and Pfizer. UMCU received minor funding (€1000–€25 000 per industrial partner) for consultation and invited lectures by AbbVie, MedImmune, Ablynx, Bavaria Nordic, MabXience, GSK, Novavax, Pfizer, Moderna, AstraZeneca, MSD, Sanofi, Genzyme, and Janssen. L. J. B. is the founding chair of the ReSViNET Foundation. J. G. W. has been an investigator for clinical trials sponsored by pharmaceutical companies, including AstraZeneca, Merck, Pfizer, Sanofi, and Janssen, with all funds paid to UMCU. J. G. W participated in the advisory board of Janssen and Sanofi, with fees paid to UMCU. All other authors report no potential conflicts. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed., (© The Author(s) 2023. Published by Oxford University Press on behalf of Infectious Diseases Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Background: There is no consensus on how to best quantify disease severity in infants with respiratory syncytial virus (RSV) and/or bronchiolitis; this lack of a sufficiently validated score complicates the provision of clinical care and, the evaluation of trials of therapeutics and vaccines. The ReSVinet score appears to be one of the most promising; however, it is too time consuming to be incorporated into routine clinical care. We aimed to develop and externally validate simplified versions of this score., Methods: Data from a multinational (the Netherlands, Spain, and United Kingdom) multicenter case-control study of infants with RSV were used to develop simplified versions of the ReSVinet score by conducting a grid search to determine the best combination of equally weighted parameters to maximize for the discriminative ability (measured by area under the receiver operating characteristic curve [AUROC]) across a range of outcomes (hospitalization, intensive care unit admission, ventilation requirement). Subsequently discriminative validity of the score for a range of secondary care outcomes was externally validated by secondary analysis of datasets from Rwanda and Colombia., Results: Three candidate simplified scores were identified using the development dataset; they were excellent (AUROC >0.9) at discriminating for a range of outcomes, and their performance was not significantly different from the original ReSVinet score despite having fewer parameters. In the external validation datasets, the simplified scores were moderate to excellent (AUROC, 0.7-1) across a range of outcomes. In all outcomes, except in a single dataset for predicting admission to the high-dependency unit, they performed at least as well as the original ReSVinet score., Conclusions: The candidate simplified scores developed require further external validation in larger datasets, ideally from resource-limited settings before any recommendation regarding their use., Competing Interests: Potential conflicts of interest . Y. L. has received funding from Wellcome Trust and GSK, outside the submitted work, and has received personal fees from Pfizer. S. B. D. has received honoraria from MSD and Sanofi for taking part in respiratory syncytial virus advisory boards and has provided consultancy and/or investigator roles in relation to product development for Janssen, AstraZeneca, Pfizer, Valneva, MSD, iLiAD, and Sanofi, with fees paid to St George's, University of London. J. G. W. participated in an advisory board for Janssen, with fees paid to the University Medical Center Utrecht. D. O. and J. A. are employees of Janssen Pharmaceutica. F. M. T. reports grants from Janssen, MSD, GSK, and AstraZeneca; personal fees from Ablynx, GSK, Pfizer, MSD, Moderna, AstraZeneca, Sanofi-Pasteur, Novavax, Seqirus, and Biofabri; nonfinancial support from GSK, Pfizer, MSD, and Seqirus; and trial fees paid to his institution from all these companies, except Biofabri. A. J. P. is chair of the UK Department of Health and Social Care's Joint Committee on Vaccination and Immunisation. The University of Oxford has entered into a partnership with AstraZeneca for the development of a coronavirus disease 2019 vaccine. L. B. has received funding through the University Medical Center Utrecht from AbbVie, Janssen, the Bill & Melinda Gates Foundation, Nutricia Danon, MeMed Diagnostics, GSK, AstraZeneca, Sanofi, Ablynx, Bavaria Nordic, MabXience, Novavax, and Pfizer. H. N. has received funding from Innovative Medicines Initiative, the National Institute for Health and Care Research, Icosavax and Pfizer and has received fees from GSK, AbbVie, AstraZeneca, Pfizer, Novavax, Sanofi, Merck, Icosavax and ReViral all paid to the insitution. All other authors report no potential conflicts. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed, (© The Author(s) 2023. Published by Oxford University Press on behalf of Infectious Diseases Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Competing Interests: Potential conflicts of interest. C. V. was a Sanofi employee at the time the work described was performed and owns Sanofi stock; and is currently employed by Vaccines Europe, part of the European Federation of Pharmaceutical Industries and Associations trade association. L. B. has regular interactions with pharmaceutical and other industrial partners and has not received personal fees or other personal benefits; is the founding chairman of the ReSViNET Foundation; his institution, University Medical Centre Utrecht, has received major funding (>€100 000 per industrial partner) for investigator-initiated studies from AbbVie, MedImmune, AstraZeneca, Sanofi, Janssen, Pfizer, MSD, and MeMed Diagnostics; major funding for the RSV GOLD study from the Bill and Melinda Gates Foundation; major funding as part of the public private partnership IMI-funded RESCEU and PROMISE projects with partners GSK, Novavax, Janssen, AstraZeneca, Pfizer, and Sanofi; major funding from Julius Clinical for participating in clinical studies sponsored by MedImmune and Pfizer; and has received minor funding (€1000–25 000 per industrial partner) for consultation and invited lectures from AbbVie, MedImmune, Ablynx, Bavaria Nordic, MabXience, GSK, Novavax, Pfizer, Moderna, Astrazeneca, MSD, Sanofi, and Janssen. C. D. was a Sanofi employee at the time the work described was performed and owns Sanofi stock; and is currently employed by Moderna and owns Moderna stock. H. N. reports grants to his institution from the Innovative Medicines Initiative, Pfizer, and Icosavax; fees for consulting or invited lectures from World Health Organization (WHO), Pfizer, the Bill and Melinda Gates Foundation, Sanofi, Abbvie, GSK, Merck, Janssen, and Novavax; and unpaid advisory roles with WHO and the ReSViNET Foundation. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed.

Competing Interests: Disclosure of interest: The authors completed the ICMJE Disclosure of Interest Form (available upon request from the corresponding author) and declare the following activities and relationships: LB has regular interaction with pharmaceutical and other industrial partners; he has not received personal fees or other personal benefits. LB is the founding chairman of the ReSViNET Foundation. His institution, the University Medical Centre Utrecht, has received funding for investigator-initiated studies from AbbVie, MedImmune, AstraZeneca, Sanofi, Janssen, Pfizer, MSD, and MeMed Diagnostics; for the RSV GOLD study from the Bill and Melinda Gates Foundation; as part of the public-private partnership IMI-funded RESCEU and PROMISE projects with partners GSK, Novavax, Janssen, AstraZeneca, Pfizer, and Sanofi; by Julius Clinical for participating in clinical studies sponsored by MedImmune and Pfizer; for consultation and invited lectures by AbbVie, MedImmune, Ablynx, Bavarian Nordic, mAbxience, GSK, Novavax, Pfizer, Moderna, AstraZeneca, MSD, Sanofi, Genzyme, and Janssen. MK reports receiving consulting fees from Pfizer and Abbott; payment or honoraria for lectures, presentations, speakers’ bureaus, manuscript writing, or educational events from GSK outside the submitted work. LH is an employee of GSK. HN reports grants from Innovative Medicines Initiative, Pfizer, and Icosavax to his institution; consulting fees from World Health Organization, Pfizer, Bill and Melinda Gates Foundation, and Sanofi to his institution; payment or honoraria for lectures, presentations, speakers bureaus, manuscript writing, or educational events from AbbVie to his institution; support for attending meetings and/or travel from Sanofi; participation in a Data Safety Monitoring Board or Advisory Board from GSK, Sanofi, Merck, World Health Organization (unpaid), Janssen, Novavax, ReSViNET (unpaid), Icosavax, and Pfizer to his institution, outside the submitted work. TN reports contract funding from GSK to his institution for clinical trials of meningococcal and other vaccines, and personal funding from GSK for scientific advice on various vaccines. He also participated on several Data Safety Monitoring Boards for vaccine trials conducted by other sponsors. HO reports grants from Japan Agency for Medical Research and Development for research in the Philippines including RSV research and from Japan Society for the Promotion of Science for RSV research, outside the submitted work. DS reports consulting fees from GSK, Seqirus, Sanofi, MSD, Pfizer, AstraZeneca, J&J, BioNTech, Moderna, and Clover BioPharmaceuticals.

Background: Currently, there are no available tools to identify infants at the highest risk of significant morbidity and mortality from respiratory syncytial virus (RSV) lower respiratory tract infection (LRTI) who would benefit most from RSV prevention products. The objective was to develop and internally validate a personalized risk prediction tool for use among all newborns that uses readily available birth/postnatal data to predict RSV LRTI requiring intensive care unit (ICU) admission., Methods: We conducted a population-based birth cohort study of infants born from 1995 to 2007, insured by the Tennessee Medicaid Program, and who did not receive RSV immunoprophylaxis during the first year of life. The primary outcome was severe RSV LRTI requiring ICU admission during the first year of life. We built a multivariable logistic regression model including demographic and clinical variables available at or shortly after birth to predict the primary outcome., Results: In a population-based sample of 429 365 infants, 713 (0.2%) had severe RSV LRTI requiring ICU admission. The median age of admission was 66 days (interquartile range, 37-120). Our tool, including 19 variables, demonstrated good predictive accuracy (area under the curve, 0.78; 95% confidence interval, 0.77-0.80) and identified infants who did not qualify for palivizumab, based on American Academy of Pediatrics guidelines, but had higher predicted risk levels than infants who qualified (27% of noneligible infants with >0.16% predicted probabilities [lower quartile for eligible infants])., Conclusions: We developed a personalized tool that identified infants at increased risk for severe RSV LRTI requiring ICU admission, expected to benefit most from immunoprophylaxis., Competing Interests: Potential conflicts of interest. T.V.H. serves on vaccine DSMBs for Pfizer and has served as a consultant to Sanofi. L.J.B. has regular interaction with pharmaceutical and other industrial partners. He has not received personal fees or other personal benefits. University Medical Centre Utrecht has received major funding (>€100 000 per industrial partner) for investigator-initiated studies from AbbVie, MedImmune, AstraZeneca, Sanofi, Janssen, Pfizer, MSD, and MeMed Diagnostics; has received major funding for the RSV GOLD study from the Bill and Melinda Gates Foundation; has received major funding as part of the public private partnership IMI-funded RESCEU and PROMISE projects with partners GSK, Novavax, Janssen, AstraZeneca, Pfizer, and Sanofi; has received major funding by Julius Clinical for participating in clinical studies sponsored by MedImmune and Pfizer; and has received minor funding (€1000-25 000 per industrial partner) for consultation and invited lectures by AbbVie, MedImmune, Ablynx, Bavaria Nordic, MabXience, GSK, Novavax, Pfizer, Moderna, Astrazeneca, MSD, Sanofi, and Janssen. L.J.B. is the founding chairman of the ReSViNET Foundation. All other authors (B.M.S., N.B.A., T.G., P.W., E.F.M., G.E.) report no conflicts of interest., (© The Author(s) 2024. Published by Oxford University Press on behalf of Infectious Diseases Society of America.)

Household studies provide an efficient means to study transmission of infectious diseases, enabling estimation of susceptibility and infectivity by person-type. A main inclusion criterion in such studies is usually the presence of an infected person. This precludes estimation of the hazards of pathogen introduction into the household. Here we estimate age- and time-dependent household introduction hazards together with within household transmission rates using data from a prospective household-based study in the Netherlands. A total of 307 households containing 1,209 persons were included from August 2020 until March 2021. Follow-up of households took place between August 2020 and August 2021 with maximal follow-up per household mostly limited to 161 days. Almost 1 out of 5 households (59/307) had evidence of an introduction of SARS-CoV-2. We estimate introduction hazards and within-household transmission rates in our study population with penalized splines and stochastic epidemic models, respectively. The estimated hazard of introduction of SARS-CoV-2 in the households was lower for children (0-12 years) than for adults (relative hazard: 0.62; 95%CrI: 0.34-1.0). Estimated introduction hazards peaked in mid October 2020, mid December 2020, and mid April 2021, preceding peaks in hospital admissions by 1-2 weeks. Best fitting transmission models included increased infectivity of children relative to adults and adolescents, such that the estimated child-to-child transmission probability (0.62; 95%CrI: 0.40-0.81) was considerably higher than the adult-to-adult transmission probability (0.12; 95%CrI: 0.057-0.19). Scenario analyses indicate that vaccination of adults can strongly reduce household infection attack rates and that adding adolescent vaccination offers limited added benefit., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 van Boven et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Context: Exclusive breastfeeding for 6 months after birth provides infants with the best start for life. A review by Bravi et al. summarized the importance of maternal diet as a determinant of human milk composition based on data up to 2015, but evidence on nutrient intake level was limited., Objective: We updated the review by Bravi et al., critically assessed differences in study designs and sampling methods, and graphically visualized trends and associations., Data Sources: PubMed was systematically searched for articles published between January 2015 and March 2021., Data Extraction: Article screening, selection, and data extraction was done by two independent researchers, including a risk of bias assessment based on 11 criteria. Articles were eligible when including: quantitative information, commonly used effect estimates, healthy mother-infant dyads., Results: Twenty seven observational and five intervention studies were identified ( n  = 7,138) and combined with results of Bravi et al. Fatty acids were still the most studied human milk components in relation to maternal diet ( n  = 17 studies) with maternal fish intake being predominantly positively associated with milk ALA ( r  = 0.28-0.42), DHA ( r  = 0.24-0.46), and EPA ( r  = 0.25-0.28) content. PUFAs from diet were generally positively correlated with their concentrations in milk, while SFA intake was negatively associated with several fatty acids in milk. Studies on associations with maternal diet and milk carbohydrates, proteins, vitamins and minerals were limited in number and varied in methods and results., Conclusion: This updated review shows that evidence on the association between maternal diet and human milk fatty acids is rapidly increasing, but still diversified in methodology and results. Further studies, preferably intervention studies, assessing diet and milk carbohydrates, proteins, vitamins and minerals are needed to be able draw conclusions on the importance of maternal diet for human milk composition as a whole., Competing Interests: IP and LL were employed by the Ausnutria BV. LB and AHH declare financial support by Danone Nutricia Research unrelated to this article. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Petersohn, Hellinga, van Lee, Keukens, Bont, Hettinga, Feskens and Brouwer-Brolsma.)

The European Medicines Agency and the US Food and Drug Administration have recently approved a maternal vaccine for respiratory syncytial virus. The US Food and Drug Administration limits vaccination to later in pregnancy. Mathematical modeling demonstrates that this vaccination window may reduce the global mortality impact of the vaccine by 12%. Policymakers should carefully consider vaccine risks and benefits to safeguard vulnerable infants effectively., Competing Interests: L.J.B. has regular interaction with pharmaceutical and other industrial partners. He has not received personal fees or other personal benefits. UMCU has received major funding (>€100,000 per industrial partner) for investigator-initiated studies from AbbVie, MedImmune, AstraZeneca, Sanofi, Janssen, Pfizer, MSD and MeMed Diagnostics. UMCU has received major funding for the RSV GOLD study from the Bill and Melinda Gates Foundation. UMCU has received major funding as part of the public-private partnership IMI-funded RESCEU and PROMISE projects with partners GSK, Novavax, Janssen, AstraZeneca, Pfizer and Sanofi. UMCU has received major funding by Julius Clinical for participating in clinical studies sponsored by MedImmune and Pfizer. UMCU received minor funding (€1,000–25,000 per industrial partner) for consultation and invited lectures by AbbVie, MedImmune, Ablynx, Bavaria Nordic, MabXience, GSK, Novavax, Pfizer, Moderna, AstraZeneca, MSD, Sanofi, Janssen. L.J.B. is the founding chairman of the ReSViNET Foundation. Since April 1, 2021, Louis has been given a new position as medical scientific division manager of the Children’s Division of the Wilhelmina Children’s Hospital in Utrecht. The other authors have no conflicts of interest to disclose., (Copyright © 2023 The Author(s). Published by Wolters Kluwer Health, Inc.)

Background: To meet regulatory approval, interventions must demonstrate efficacy against a primary outcome in randomized clinical trials. However, when there are multiple clinically relevant outcomes, selecting a single primary outcome is challenging. Incorporating data from multiple outcomes may increase statistical power in clinical trials. We examined methods for analyzing data on multiple endpoints, inspired by real-world trials of interventions against respiratory syncytial virus (RSV)., Method: We developed a novel permutation test representing a weighted average of individual outcome test statistics ( wavP ) to evaluate intervention efficacy in a multiple endpoint analysis. We compared the power and type I error rate of this approach to the Bonferroni correction ( bonfT ) and the minP permutation test. We evaluated the different approaches using simulated data from three hypothetical trials varying the intervention efficacy, correlation, and incidence of the outcomes, and data from a real-world RSV clinical trial., Results: When the vaccine efficacy against different outcomes was similar, wavP yielded higher power than bonfT and minP ; in some scenarios the improvement in power was substantial. In settings where vaccine efficacy was notably larger against one endpoint compared with the others, all three methods had similar power. We developed an R package, PERmutation basEd ANalysis of mulTiple Endpoints (PERMEATE), to guide the selection of the most appropriate method for analyzing multiple endpoints in clinical trials., Conclusions: Analyzing multiple endpoints using a weighted permutation method can increase power, whereas controlling the type I error rate compared with established methods under conditions mirroring real-world RSV clinical trials., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

Whereas most infants infected with respiratory syncytial virus (RSV) show no or only mild symptoms, an estimated 3 million children under five are hospitalized annually due to RSV disease. This study aimed to investigate biological mechanisms and associated biomarkers underlying RSV disease heterogeneity in young infants, enabling the potential to objectively categorize RSV-infected infants according to their medical needs. Immunophenotypic and functional profiling demonstrated the emergence of immature and progenitor-like neutrophils, proliferative monocytes (HLA-DR Low , Ki67+), impaired antigen-presenting function, downregulation of T cell response and low abundance of HLA-DR Low B cells in severe RSV disease. HLA-DR Low monocytes were found as a hallmark of RSV-infected infants requiring hospitalization. Complementary transcriptomics identified genes associated with disease severity and pointed to the emergency myelopoiesis response. These results shed new light on mechanisms underlying the pathogenesis and development of severe RSV disease and identified potential new candidate biomarkers for patient stratification., (© 2023 The Authors. Clinical and Translational Medicine published by John Wiley & Sons Australia, Ltd on behalf of Shanghai Institute of Clinical Bioinformatics.)

Background: Mucosal administration of monoclonal antibodies (mAbs) against respiratory pathogens is a promising alternative for systemic administration because lower doses are required for protection. Clinical development of mucosal mAbs is a highly active field yet clinical proof-of-concept is lacking., Methods: In this investigator-initiated, double-blind, randomized placebo-controlled trial, we evaluated intranasal palivizumab for the prevention of RSV infection in preterm infants (Dutch Trial Register NTR7378 and NTR7403). We randomized infants 1:1 to receive intranasal palivizumab (1 mg/mL) or placebo once daily during the RSV season. Any RSV infection was the primary outcome and RSV hospitalization was the key secondary outcome. The primary outcome was analyzed with a mixed effect logistic regression on the modified intention-to-treat population., Findings: We recruited 268 infants between Jan 14, 2019 and Jan 28, 2021, after which the trial was stopped for futility following the planned interim analysis. Adverse events were similar in both groups (22/134 (16.4%) palivizumab arm versus 26/134 (19.4%) placebo arm). There were 6 dropouts and 168 infants were excluded from the efficacy analyses due to absent RSV circulation during the SARS-CoV-2 pandemic. Any RSV infection was similar in infants in both groups (18/47 (38.3%) palivizumab arm versus 11/47 (23.4%) placebo arm; aOR 2.2, 95% CI 0.7-6.5)., Interpretation: Daily intranasal palivizumab did not prevent RSV infection in late preterm infants. Our findings have important implications for the clinical development of mucosal mAbs, namely the necessity of timely interim analyses and further research to understand mucosal antibody half-life., Funding: Funded by the Department of Pediatrics, University Medical Centre Utrecht, the Netherlands., Competing Interests: UMCU has received major funding (>€100,000 per industrial partner) for investigator initiated studies from AbbVie, MedImmune, AstraZeneca, Sanofi, Janssen, Pfizer, MSD and MeMed Diagnostics. UMCU has received major funding for from the Bill and Melinda Gates Foundation, Gates Medical Research Institute and the Dutch Lung Foundation. UMCU has received major funding as part of the public private partnership IMI-funded RESCEU and PROMISE projects with partners GSK, Novavax, Janssen, AstraZeneca, Pfizer and Sanofi. UMCU has received major funding by Julius Clinical for participating in clinical studies sponsored by MedImmune and Pfizer. UMCU received minor funding (€1000–25,000 per industrial partner) for consultation and invited lectures by AbbVie, MedImmune, Ablynx, Bavaria Nordic, MabXience, GSK, Novavax, Pfizer, Moderna, Astrazeneca, MSD, Sanofi, Janssen. LJB and NIM have regular interaction with pharmaceutical and other industrial partners. They have not received personal fees or other personal benefits. LJB is the founding chairman of the ReSViNET Foundation. Narsyn study group Elisabeth E. Nibbelke MSc1, Brigitte Buiteman, Neele Rave MSc1, Marlies Vermaas-van Putten MD2, Elly A. Smit-Kleinlugtenbeld MD3, Jacqueline P. de Lege-Korstanje Msc3, Marieke G. Peetsold MD PhD4, Anthon Hulsmann MD PhD5, Sandy van Gool MD PhD6, Yvonne Snepvangers MD PhD7, Max Colombijn MD PhD7, Negassi Menelik MD8, Stephanie de Crom MD PhD9, Ben Semmekrot MD PhD10, Wouter J. de Waal MD PhD11, Eline Okhuijsen MD11, Gavin W. ten Tusscher MD PhD12, Ronald A. de Moor MD13, Mijke A. Breukels MD PhD14, Claire Lutterman MD15, Gerdien A. Tramper-Stranders MD PhD16, Johanna H. Oudshoorn MD PhD17, Astrid Ritman17, Jeannette S. von Lindern MD PhD18, Gerdina H. Dubbink-Verheij MD PhD18, Maartje M. van den Berg MD PhD19, Marlon E.F. Wilsterman MD20, Edwin Rietveld MD PhD21, Willemijn van Heel MD22, Anne M. de Grauw MD22, Femke Croes MD23, Rienus A. Doedens MD24, Lonneke van Onzenoort-Bokken MD PhD25, Clemens B. Meijssen MD26, Machteld van Scherpenzeel-de Vries MD27, Petra Hoekstra MD27, Linda G.M. van Rooij MD PhD28, Willem-Pieter de Boode MD PhD29, Maaike C. van Rossem MD30, Petra Sipkema MSc30, Monique A.M. Jacobs MD31, Marianne A. van Houten MD PhD32, Indrani Kok-Wijesinha MD33, Arine M. Vlieger MD PhD34, Walter Balemans MD PhD34, Frans B. Plötz MD PhD35, Naomi Reijmerink MD PhD36, Stefan M. van Dorth MD37, Willem Heikens MD37, Anke G. Kuijpers38, Christel Geesing MD38, Bas J.P. Delsing MD39, Mieke Aldenhoven MD PhD40, Karoly Illy MD40, Eric Hack40, Floris Groenendaal MD PhD41, Nicole Derksen42, Katrien Oude Rengerink PhD43, Jan Meeldijk44, Lysette Ebskamp- van Raaij45, Jolanda D.F. de Groot-Mijnes46 PhD, Rob Schuurman PhD46. Affiliations 1Department of Pediatric Infectious Diseases and Immunology, Wilhelmina Children’s Hospital, University Medical Center Utrecht, the Netherlands 2Pediatric Department, Admiraal de Ruyter Ziekenhuis, Goes, the Netherlands 3Pediatric Department, Albert Schweitzer Ziekenhuis, Dordrecht, the Netherlands 4Pediatric Department, Alrijne Ziekenhuis, Leiderdorp, the Netherlands 5Pediatric Department, Amphia Ziekenhuis, Breda, the Netherlands 6Pediatric Department, Antonius Ziekenhuis, Sneek, the Netherlands 7Pediatric Department, Beatrix Ziekenhuis, Gorinchem, the Netherlands 8Pediatric Department, BovenIJ Ziekenhuis, Amsterdam, the Netherlands 9Pediatric Department, Bravis Ziekenhuis, Roosendaal, the Netherlands 10Pediatric Department, Canisius Wilhelmina Ziekenhuis, Nijmegen, the Netherlands 11Pediatric Department, Diakonessenhuis, Utrecht, the Netherlands 12Pediatric Department, Dijklander Ziekenhuis, Hoorn, the Netherlands 13Pediatric Department, Elisabeth-Tweesteden Ziekenhuis, Tilburg, the Netherlands 14Pediatric Department, Elkerliek Ziekenhuis, Helmond, the Netherlands 15Pediatric Department, Flevoziekenhuis, Almere, the Netherlands 16Pediatric Department, Franciscus Gasthuis en Vlietland, Rotterdam, the Netherlands 17Pediatric Department, Gelre Ziekenhuis, Apeldoorn, the Netherlands 18Pediatric Department, Groene Hart Ziekenhuis, Gouda, the Netherlands 19Pediatric Department, Haaglanden Medisch Centrum, Den Haag, the Netherlands 20Pediatric Department, Nij Smellinghe Ziekenhuis, Drachten, the Netherlands 21Pediatric Department, IJsselland Ziekenhuis, Capelle aan den IJssel, the Netherlands 22Pediatric Department, Juliana Children’s Hospital, Den Haag, the Netherlands 23Pediatric Department, LangeLand Ziekenhuis, Zoetermeer, the Netherlands 24Pediatric Department, Martini Ziekenhuis, Groningen, the Netherlands 25Pediatric Department, Máxima Medisch Centrum, Veldhoven, the Netherlands 26Pediatric Department, Meander Medisch Centrum, Amersfoort, the Netherlands 27Pediatric Department, Medisch Centrum Leeuwarden, Leeuwarden, the Netherlands 28Pediatric Department, Medisch Spectrum Twente, Enschede, the Netherlands 29Pediatric Department, Radboud UMC, Nijmegen, the Netherlands 30Pediatric Department, Rijnstate, Arnhem, the Netherlands 31Pediatric Department, Slingeland Ziekenhuis, Doetinchem, the Netherlands 32Pediatric Department, Spaarne Gasthuis, Haarlem, the Netherlands 33Pediatric Department, St. Anna Ziekenhuis, Geldrop, the Netherlands 34Pediatric Department, St. Antonius Ziekenhuis, Nieuwegein & Utrecht, the Netherlands 35Pediatric Department, Tergooi Ziekenhuis, Hilversum, the Netherlands 36Pediatric Department, Ziekenhuis St. Jansdal, Harderwijk, the Netherlands 37Pediatric Department, Ziekenhuis Tjongerschans, Heerenveen, the Netherlands 38Pediatric Department, Ziekenhuis Bernhoven, Uden, the Netherlands 39Pediatric Department, Ziekenhuisgroep Twente, Almelo, the Netherlands 40Pediatric Department, Ziekenhuis Rivierenland, Tiel, the Netherlands 41Neonatology Department, Wilhelmina Children’s Hospital, University Medical Center Utrecht, the Netherlands 42RSV Independent Patient Advisory Board 43Julius Center for Health Sciences and Primary Care, Section Biostatistics and Research Support, University Medical Center Utrecht, the Netherlands 44Center for Translational Immunology, University Medical Center Utrecht, the Netherlands 45Utrecht Center for Diagnostic Advances in Immunology Research (UDAIR), University Medical Center Utrecht, the Netherlands 46Department of Medical Microbiology, University Medical Center Utrecht, the Netherlands, (© 2023 The Authors.)

We initiated a nationwide prospective study to monitor respiratory syncytial virus (RSV)-related pediatric hospitalizations in 46 hospitals throughout the Netherlands between May 2021 and August 2022. We showed year-round RSV transmission in the Netherlands after an initial 2021 summer outbreak. The pattern was unprecedented and distinct from neighboring countries. We extended a dynamic simulation model to evaluate the impact of waning immunity on pediatric RSV hospitalizations in the Netherlands using 4 different scenarios. Our results suggest that the observed continuous RSV transmission pattern could be associated with waning immunity due to the period of very low RSV circulation during the COVID-19 pandemic., Competing Interests: Potential conflicts of interest. L. B. has regular interaction with pharmaceutical and other industrial partners but has not received personal fees or other personal benefits. University Medical Center Utrecht (UMCU) has received major funding (>€100 000 per industrial partner) for investigator-initiated studies from AbbVie, MedImmune, Janssen, the Bill & Melinda Gates Foundation, Nutricia (Danone), and MeMed Diagnostics; major cash or in-kind funding as part of the public–private partnership Innovative Medicines Initiative–funded RESCEU project from GSK, Novavax, Janssen, AstraZeneca, Pfizer, and Sanofi; major funding by Julius Clinical for participating in the INFORM study sponsored by MedImmune; minor funding for participation in trials by Regeneron and Janssen during 2015–2017 (total annual estimate less than €20 000); and minor funding for consultation and invited lectures by AbbVie, MedImmune, Ablynx, Bavaria Nordic, MabXience, Novavax, Pfizer, and Janssen (total annual estimate less than €20 000). L. B. is the founding chairman of the ReSViNET Foundation. V. E. P. has received reimbursement from Merck and Pfizer for travel expenses to scientific input engagements on respiratory syncytial virus. D. M. W. has received consulting fees from Pfizer, Merck, GSK, Affinivax, and Matrivax for work unrelated to this manuscript and is the principal investigator on research grants from Pfizer and Merck on work unrelated to this manuscript. Z. Z. is expected to receive consulting fees from Pfizer for work unrelated to this manuscript. All other authors report no potential conflicts. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed., (© The Author(s) 2023. Published by Oxford University Press on behalf of Infectious Diseases Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

The large global burden of respiratory syncytial virus (RSV) respiratory tract infections in young children and older adults has gained increased recognition in recent years. Recent discoveries regarding the neutralization-specific viral epitopes of the pre-fusion RSV glycoprotein have led to a shift from empirical to structure-based design of RSV therapeutics, and controlled human infection model studies have provided early-stage proof of concept for novel RSV monoclonal antibodies, vaccines and antiviral drugs. The world's first vaccines and first monoclonal antibody to prevent RSV among older adults and all infants, respectively, have recently been approved. Large-scale introduction of RSV prophylactics emphasizes the need for active surveillance to understand the global impact of these interventions over time and to timely identify viral mutants that are able to escape novel prophylactics. In this Review, we provide an overview of RSV interventions in clinical development, highlighting global disease burden, seasonality, pathogenesis, and host and viral factors related to RSV immunity., (© 2023. Springer Nature Limited.)

Competing Interests: LJB has regular interaction with pharmaceutical and other industrial partners but has not received personal fees or other personal benefits, and is the founding chairman of the ReSViNET Foundation. JGW has been an investigator for clinical trials sponsored by pharmaceutical companies including AstraZeneca, Merck, Pfizer, Sanofi, and Janssen with all funds paid to University Medical Center Utrecht, and has participated in the advisory boards of Janssen and Sanofi with fees paid to UMCU.

Background: Millions of children are hospitalised due to respiratory syncytial virus (RSV) infection every year. Treatment is supportive, and current therapies (e.g. inhaled bronchodilators, epinephrine, nebulised hypertonic saline, and corticosteroids) are ineffective or have limited effect. Respiratory syncytial virus immunoglobulin may be used prophylactically to prevent hospital admission from RSV-related illness. It may be considered for the treatment of established severe RSV infection or for treatment in an immunocompromised host, although it is not licensed for this purpose. It is unclear whether immunoglobulins improve outcomes when used as a treatment for established RSV infection in infants and young children admitted to hospital. This is an update of a review first published in 2019., Objectives: To assess the effects of immunoglobulins for the treatment of RSV-proven lower respiratory tract infections (LRTIs) in children aged up to three years, admitted to hospital., Search Methods: For this 2022 update, we searched the Cochrane Central Register of Controlled Trials (CENTRAL), which contains the Cochrane Acute Respiratory Infections Specialised Register, Ovid MEDLINE, Embase, CINAHL, and Web of Science (from inception to 2 December 2022) with no restrictions. We searched two trial registries for ongoing trials (to 2 December 2022) and checked the reference lists of reviews and included articles for additional studies., Selection Criteria: Randomised controlled trials comparing immunoglobulins with placebo in hospitalised infants and children aged up to three years with laboratory-diagnosed RSV lower respiratory tract infection., Data Collection and Analysis: Two review authors independently selected trials, assessed risk of bias, and extracted data. We assessed evidence certainty using GRADE., Main Results: In total, we included eight trials involving 906 infants and children aged up to three years. We included one new trial in this update. The immunoglobulin preparations used in these trials included anti-RSV immunoglobulin and the monoclonal antibody preparations palivizumab and motavizumab. Five trials were conducted at single or multiple sites within a single high-income country (four in the USA, one in Qatar). Three trials included study sites in different countries. All three of these trials included study sites in one or more high-income countries (USA, Chile, New Zealand, Australia, Qatar), with two trials also including a study site in a middle-income country (Panama). Five of the eight trials were "supported" or "sponsored" by the trial drug manufacturers. The evidence is very uncertain about the effect of immunoglobulins on mortality (risk ratio (RR) 0.87, 95% confidence interval (CI) 0.14 to 5.27; 4 studies, 309 participants). There were four deaths - two amongst 98 children receiving immunoglobulins, and two amongst 98 children receiving placebo. One additional death occurred in a fourth trial, however the study group of the child was not known and the data were not included in the analysis (very low-certainty evidence). The use of immunoglobulins in infants and children admitted to hospital with RSV proven LRTI probably results in little to no difference in the length of hospitalisation (mean difference (MD) -0.13 days, 95% CI -0.37 to 0.12; 6 studies, 737 participants; moderate-certainty evidence). Immunoglobulins may result in little to no difference in the number of children who experience one or more adverse events of any severity or seriousness compared to placebo (RR 1.18, 95% CI 0.78 to 1.78; 5 studies, 340 participants; low-certainty evidence) or the number of children who experience one or more adverse events judged by study investigators to be serious in nature, compared to placebo (RR 1.08, 95% CI 0.65 to 1.79; 4 studies, 238 participants; low-certainty evidence). Certainty of evidence for secondary outcomes was low. This evidence suggests that use of immunoglobulins results in little to no difference in the need for, or duration of, mechanical ventilation and the need for, or duration of, supplemental oxygen. The use of immunoglobulins does not reduce the need for admission to the intensive care unit (ICU) and when children are admitted to the ICU results in little to no difference in the duration of ICU stay., Authors' Conclusions: We are very uncertain about the effect of immunoglobulins on mortality. We are moderately certain that use of immunoglobulins in hospitalised infants and children may result in little to no difference in the length of hospitalisation. Immunoglobulins may result in little to no difference in adverse events, the need for or duration of mechanical ventilation, supplemental oxygen, or admission to the intensive care unit, though we are less certain about this evidence and the true effect of immunoglobulins on these outcomes may differ markedly from the estimated effect observed in this review. All trials were conducted in high-income countries, and data from populations in which the rate of death from RSV infection is higher are lacking., (Copyright © 2023 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.)

Introduction: The immune mechanisms supporting partial protection from reinfection and disease by the respiratory syncytial virus (RSV) have not been fully characterized. In older adults, symptoms are typically mild but can be serious in patients with comorbidities when the infection extends to the lower respiratory tract., Methods: This study formed part of the RESCEU older-adults prospective-cohort study in Northern Europe (2017-2019; NCT03621930) in which a thousand participants were followed over an RSV season. Peripheral-blood samples (taken pre-season, post-season, during illness and convalescence) were analyzed from participants who (i) had a symptomatic acute respiratory tract infection by RSV (RSV-ARTI; N=35) or (ii) asymptomatic RSV infection (RSV-Asymptomatic; N=16). These analyses included evaluations of antibody (Fc-mediated-) functional features and cell-mediated immunity, in which univariate and machine-learning (ML) models were used to explore differences between groups., Results: Pre-RSV-season peripheral-blood biomarkers were predictive of symptomatic RSV infection. T-cell data were more predictive than functional antibody data (area under receiver operating characteristic curve [AUROC] for the models were 99% and 76%, respectively). The pre-RSV season T-cell phenotypes which were selected by the ML modelling and which were more frequent in RSV-Asymptomatic group than in the RSV-ARTI group, coincided with prominent phenotypes identified during convalescence from RSV-ARTI (e.g., IFN-γ+, TNF-α+ and CD40L+ for CD4+, and IFN-γ+ and 4-1BB+ for CD8+)., Conclusion: The evaluation and statistical modelling of numerous immunological parameters over the RSV season suggests a primary role of cellular immunity in preventing symptomatic RSV infections in older adults., Competing Interests: Authors CV and AM were employed by the company Sanofi during the development of the study and own stock options in the company. Authors SB-J, AB, JA and DÖ were employed by the company Janssen Pharmaceutica NV. Authors SB-J, AB and JA own stocks from Johnson & Johnson. Authors MJ, BS, CL, and JD were employed by the company GSK, and BS and CL own stocks from the company. Author CL had submitted a patent application for COMPOSITIONS AND METHODS FOR IMPROVING THE IMMUNE RESPONSE TO SARS-COV2. During this time, he was a GSK representative as a co-leader for a subgroup in the Adventitious Virus Detection Technologies Interest Groups AVDTIG. Author SD has been an investigator for clinical trials of vaccines and antimicrobials for pharmaceutical companies including AstraZeneca, Merck, Pfizer, Valneva, Iliad, Sanofi, and Janssen, and previously sat on RSV advisory boards for Sanofi and Merck. Author JW was a member of Janssen and Sanofi advisory boards. She also worked closely together with author LB on many projects and clinical studies for which LB received grants. Author AP received grants from: Gates, Wellcome, MRC, NIHR and European Commission IMI RESCEU. During this time the laboratory assays were provided by GSK. Author AP is a contributor to intellectual property licensed by Oxford University Innovation to AstraZeneca. He also received consulting fees from Shionogi. He was chair of DHSC’s Joint Committee on Vaccination and Immunisation and also a member of WHOs SAGE until 2022. Author PO received the RESCEU EU IMI award and consulting fees from: GSK, Moderna, Janssen, Seqirus and Pfizer. He also received payments or honoraria from Moderna, Medscape and support for attending meetings for Moderna. During this project he was also a school governor for Sidcot, Somerset. He received grants from UKRI and MRC EMINENT. Author LB has regular interaction with pharmaceutical and other industrial partners. UMCU has received funding for investigator-initiated studies from AbbVie, MedImmune, AstraZeneca, Sanofi, Janssen, Pfizer, MSD and MeMed Diagnostics. UMCU has received funding for the RSV GOLD study from the Bill and Melinda Gates Foundation. UMCU has received funding as part of the public private partnership IMI funded RESCEU and PROMISE projects with partners GSK, Novavax, Janssen, AstraZeneca, Pfizer and Sanofi. UMCU has received funding by Julius Clinical for participating in clinical studies sponsored by MedImmune and Pfizer. UMCU received funding for consultation and invited lectures by AbbVie, MedImmune, Ablynx, Bavaria Nordic, MabXience, GSK, Novavax, Pfizer, Moderna, Astrazeneca, MSD, Sanofi, Genzyme, Janssen. Author LB is the founding chairman of the ReSViNET Foundation. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Salaun, De Smedt, Vernhes, Moureau, Öner, Bastian, Janssens, Balla-Jhagjhoorsingh, Aerssens, Lambert, Coenen, Butler, Drysdale, Wildenbeest, Pollard, Openshaw and Bont.)

Competing Interests: DDL received consultancy and lecture fees from Chiesi Farmaceutici, Getinge, Vyaire, Radiometer, Medtronic, Astra Zeneca, Boehringer Ingelheim, Airway Therapeutics, Natus, Masimo; he also has equity options from Ophirex ltd. All these were unrelated to the present work and to nirsevimab and the universal RSV immunisation. MSL received consultancy and lecture fees from Medtronic, Astra Zeneca, and Sanofi, all outside of the present work and unrelated to nirsevimab and the universal RSV immunisation. EB received consultancy and lecture fees and participated to advisory boards for Astra-Zeneca and Sanofi, all outside of the present work. LB is the founding chairman of the ReSViNET Foundation. He has not received any personal benefit. His institution has conversely received research grants from AbbVie, MedImmune, AstraZeneca, Sanofi, Janssen, Pfizer, MSD and MeMed Diagnostics, GSK and Novavax, Julius Clinical. His institution also received consultancy and invited lecture fees by AbbVie, MedImmune, Ablynx, Bavaria Nordic, MabXience, GSK, Novavax, Pfizer, Moderna, Astrazeneca, MSD, Sanofi and Janssen. All these were unrelated to the present work. KS has no conflict of interest to declare. This work did not receive any funding.

Introduction: Maternal vaccination is a promising strategy to reduce the burden of vaccine-preventable diseases for mothers and infants. We aimed to provide an up-to-date overview of the efficacy and safety of all available maternal vaccines., Methods: We searched PubMed, Embase, CENTRAL and ClinicalTrials.gov on 1 February 2022, for phase III and IV randomised controlled trials (RCTs) that compared maternal vaccination against any pathogen with placebo or no vaccination. Primary outcomes were laboratory-confirmed or clinically confirmed disease in mothers and infants. Secondary safety outcomes included intrauterine growth restriction, stillbirth, maternal death, preterm birth, congenital malformations and infant death. Random effects meta-analysis were used to calculate pooled risk ratio's (RR). Quality appraisal was performed using the Grading of Recommendations, Assessment, Development and Evaluation (GRADE)., Results: Six RCTs on four maternal vaccines, influenza, tetanus, diphtheria and pertussis (Tdap), pneumococcal and respiratory syncytial virus (RSV) were eligible. The overall risk of bias and certainty of evidence varied from low to high. Maternal influenza vaccination significantly reduced the number of laboratory-confirmed influenza cases (RR 0.58, 95% CI 0.42 to 0.79, event rate 57 vs 98, 2 RCTs, n=6003, I 2 =0%), and clinically confirmed influenza cases in mothers (RR 0.88, 95% CI 0.78 to 0.99, event rate 418 vs 472, 2 RCTs, n=6003, I 2 =0%), and laboratory-confirmed influenza in infants (RR 0.66, 95% CI 0.52 to 0.85, event rate 98 vs 148, 2 RCTs, n=5883, I 2 =0%), although this was not significant for clinically confirmed influenza in infants (RR 0.99, 95% CI 0.94 to 1.05, event rate 1371 vs 1378, 2 RCTs, n=5883, I 2 =0%). No efficacy data were available on maternal Tdap vaccination. Maternal pneumococcal vaccination did not reduce laboratory-confirmed and clinically confirmed middle ear disease (RR 0.49, 95% CI 0.24 to 1.02, event rate 9 vs 18, 1 RCT, n=133 and RR 0.88 95% CI 0.69 to 1.12, event rate 42 vs 47, 1 RCT, n=133, respectively), and clinically confirmed lower-respiratory tract infection (LRTI) (RR 1.08, 95% CI 0.82 to 1.43, event rate 18 vs 34, 1 RCT, n=70) in infants. Maternal RSV vaccination did not reduce laboratory-confirmed RSV LRTI in infants (RR 0.75, 95% CI 0.56 to 1.01, event rate 103 vs 71, 1 RCT, n=4527). There was no evidence of a significant effect of any of the maternal vaccines on the reported safety outcomes., Conclusions: The few RCTs with low event rates suggest that, depending on the type of maternal vaccine, the vaccine might effectively prevent disease and within its size does not show safety concerns in mothers and infants., Prospero Registration Number: CRD42021235115., Competing Interests: Competing interests: JW participated in the advisory board of Janssen with fees paid to UMCU. MS leads a department that conducts studies on COVID-19 vaccines for the European Medicines Agency, Pfizer, AstraZeneca and Janssen. All according to the ENCePP code of conduct. KB is principal investigator of a phase 3 clinical trial on maternal RSV vaccination funded by Pfizer and of work package three of the Consign study funded by EMA. LJB has regular interaction with pharmaceutical and other industrial partners. He has not received personal fees or other personal benefits. UMCU has received major funding (>€100 000 per industrial partner) for investigator initiated studies from AbbVie, MedImmune, Janssen, the Bill and Melinda Gates Foundation, Nutricia (Danone) and MeMed Diagnostics. UMCU has received major cash or in kind funding as part of the public private partnership IMI-funded RESCEU project from GSK, Novavax, Janssen, AstraZeneca, Pfizer and Sanofi. UMCU has received major funding by Julius Clinical for participating in the INFORM study sponsored by MedImmune. UMCU has received minor funding for participation in trials by Regeneron and Janssen from 2015 to 2017 (total annual estimate less than €20 000). UMCU received minor funding for consultation and invited lectures by AbbVie, MedImmune, Ablynx, Bavaria Nordic, MabXience, Novavax, Pfizer, Janssen (total annual estimate less than €20 000). LJB is the founding chairman of the ReSViNET Foundation. All other authors have nothing to disclose (OB, EP, FA and NvdM)., (© Author(s) (or their employer(s)) 2023. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: Respiratory syncytial virus (RSV) is a leading cause of childhood mortality in infants below 6 months of age. In low-income and middle-income countries (LMICs), the public health burden is substantial and resources are limited. It is critical to inform decision makers about effectiveness of new interventions., Methods: We developed a mathematical model where individual RSV subtype A (RSV-A) and B (RSV-B) maternally derived neutralizing titers were predicted at time of birth after maternal vaccination with the RSV prefusion F protein-based vaccine. We estimated the subsequent duration of vaccine-induced immunity and compared this to the age at time of death distribution in the RSV GOLD Mortality Database to predict the potential impact of maternal vaccination on RSV-related childhood mortality. We used country-specific timing of antenatal care visits distributions and mortality estimates to make country-specific predictions for number of cases averted., Findings: The model predicts that on average a neonate born at 40 weeks gestational age will be protected between 6 and 7 months from RSV-A and approximately 5 months from RSV-B related mortality. We estimated the potential impact of RSV-related mortality for in-hospital and out-of-hospital cases in LMICs and predicted that in 51 GAVI-eligible countries maternal vaccination could avert between 55% and 63% of the RSV-related in-hospital mortality cases below 6 months of age., Interpretation: We show that maternal vaccination could substantially decrease RSV-A and RSV-B related in-hospital and out-of-hospital mortality in LMICs in the first 6 months of life., Competing Interests: The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: LB has regular interaction with pharmaceutical and other industrial partners. He has not received personal fees or other personal benefits. UMCU has received major funding (>€100,000 per industrial partner) for investigator initiated studies from AbbVie, MedImmune, AstraZeneca, Sanofi, Janssen, Pfizer, MSD, and MeMed Diagnostics. UMCU has received major funding for the RSV GOLD study from the Bill and Melinda Gates Foundation. UMCU has received major funding as part of the public private partnership IMI-funded RESCEU and PROMISE projects with partners GSK, Novavax, Janssen, AstraZeneca, Pfizer, and Sanofi. UMCU has received major funding by Julius Clinical for participating in clinical studies sponsored by MedImmune and Pfizer. UMCU received minor funding (€1,000–25,000 per industrial partner) for consultation and invited lectures by AbbVie, MedImmune, Ablynx, Bavaria Nordic, MabXience, GSK, Novavax, Pfizer, Moderna, Astrazeneca, MSD, Sanofi, Genzyme, Janssen. Dr. Bont is the founding chairman of the ReSViNET Foundation. Since April 1st 2021, LB has been given a new position as medical scientific division manager of the Children's Division of the Wilhelmina Children's Hospital in Utrecht., (© 2023 The Author(s).)

Background: Esophageal atresia (EA) is most often accompanied by some degree of tracheomalacia (TM), which negatively influences the airway by ineffective clearance of secretions. This can lead to lower airway bacterial colonization (LABC), which may cause recurrent respiratory tract infections (RTIs). This study aims to evaluate the prevalence and specific pathogens of LABC in EA patients., Methods: A 5-year retrospective single-site cohort study was conducted including all EA patients that had undergone an intraoperative bronchoalveolar lavage (BAL) during various routine surgical interventions. Concentrations of greater than 10 cfu were considered evidence of LABC., Results: We recruited 68 EA patients, of which 12 were excluded based on the exclusion criteria. In the remaining 56 patients, a total of 90 BAL samples were obtained. In 57% of the patients, at least 1 BAL sample was positive for LABC. Respiratory symptoms were reported in 21 patients at the time of the BAL, of which 10 (48%) had LABC. Haemophilus influenzae (14%) and Staphylococcus aureus (16%) were most frequently found in the BAL samples. The number of respiratory tract infections and the existence of a recurrent fistula were significantly associated with LABC ( P = 0.008 and P = 0.04, respectively)., Conclusions: This is the first study showing that patients with EA have a high prevalence of bacterial colonization of the lower airways which may be a leading mechanism of severe and recurrent respiratory complications., Competing Interests: The authors have no conflicts of interest to disclose., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

Background: Nirsevimab is an extended half-life monoclonal antibody to the respiratory syncytial virus (RSV) fusion protein that has been developed to protect infants for an entire RSV season. Previous studies have shown that the nirsevimab binding site is highly conserved. However, investigations of the geotemporal evolution of potential escape variants in recent (ie, 2015-2021) RSV seasons have been minimal. Here, we examine prospective RSV surveillance data to assess the geotemporal prevalence of RSV A and B, and functionally characterise the effect of the nirsevimab binding-site substitutions identified between 2015 and 2021., Methods: We assessed the geotemporal prevalence of RSV A and B and nirsevimab binding-site conservation between 2015 and 2021 from three prospective RSV molecular surveillance studies (the US-based OUTSMART-RSV, the global INFORM-RSV, and a pilot study in South Africa). Nirsevimab binding-site substitutions were assessed in an RSV microneutralisation susceptibility assay. We contextualised our findings by assessing fusion-protein sequence diversity from 1956 to 2021 relative to other respiratory-virus envelope glycoproteins using RSV fusion protein sequences published in NCBI GenBank., Findings: We identified 5675 RSV A and RSV B fusion protein sequences (2875 RSV A and 2800 RSV B) from the three surveillance studies (2015-2021). Nearly all (25 [100%] of 25 positions of RSV A fusion proteins and 22 [88%] of 25 positions of RSV B fusion proteins) amino acids within the nirsevimab binding site remained highly conserved between 2015 and 2021. A highly prevalent (ie, >40·0% of all sequences) nirsevimab binding-site Ile206Met:Gln209Arg RSV B polymorphism arose between 2016 and 2021. Nirsevimab neutralised a diverse set of recombinant RSV viruses, including new variants containing binding-site substitutions. RSV B variants with reduced susceptibility to nirsevimab neutralisation were detected at low frequencies (ie, prevalence <1·0%) between 2015 and 2021. We used 3626 RSV fusion-protein sequences published in NCBI GenBank between 1956 and 2021 (2024 RSV and 1602 RSV B) to show that the RSV fusion protein had lower genetic diversity than influenza haemagglutinin and SARS-CoV-2 spike proteins., Interpretation: The nirsevimab binding site was highly conserved between 1956 and 2021. Nirsevimab escape variants were rare and have not increased over time., Funding: AstraZeneca and Sanofi., Competing Interests: Declaration of interests DW, CM, BA, AAA, TB, VG, EJK, KMT, and MTE are current employees of and hold stock or stock options in AstraZeneca. MEA and DET are former employees of and hold stock or stock options in AstraZeneca. EB has received honoraria from AstraZeneca and Sanofi for lectures, presentations, speaker bureaus, manuscript writing, or educational events. TH has participated in Data Safety Monitoring Boards and ad-hoc advisory boards for Sanofi, Data Safety Monitoring Boards for Enanta, and ad-hoc advisory boards for Janssen and has received honoraria from Janssen and Merck, Sharp & Dohme (MSD) for lectures at academic meetings. CK has received honoraria from F Hoffmann-La Roche for lectures. FM-T's research activities are supported by grants from Instituto de Salud Carlos III (grant numbers: PI16/01569, PI19/01090, PI22/00406, and CB21/06/00103), GEN-COVID (grant number: IN845D 2020/23), and Grupos de Referencia Competitiva (grant number: IIN607A2021/05), and he has received additional grants to his institution from AstraZeneca and Sanofi; he also received honoraria from GlaxoSmithKline, Pfizer, Sanofi Pasteur, MSD, Seqirus, Biofabri, and Janssen for taking part in advisory boards and expert meetings and for acting as speaker in congresses outside the scope of the submitted work, in addition to travel support from GlaxoSmithKline, MSD, Pfizer, and Sanofi. FM-T has also participated in advisory boards for Pfizer, MSD, Sanofi, and GlaxoSmithKline, and in Data Safety Monitoring Boards for Biofabri; is a member of The European Technical Advisory Group of Experts—WHO Europe and the Spanish Paediatric Infectious Diseases Society; and has also acted as principal investigator in randomised controlled trials for AstraZeneca, Biofabri Seqirus, GlaxoSmithKline, Janssen, MSD, Novavax, Novartis, Pfizer, Roche, Regeneron, and Sanofi Pasteur with honoraria paid to his institution. MCN has received grants from the Bill & Melinda Gates Foundation, European and Developing Countries Clinical Trials, Pfizer, and Sanofi Pasteur; honoraria from Sanofi for lectures presentations, speakers' bureaus, manuscript writing or educational events; payment for expert testimony from Pfizer and Sanofi Pasteur; and is a board member for Gavi vaccine alliance. JMP has received payments to his institution from the Canadian Paediatric Review and Yearly RSV Coordinators Workshop and is an unpaid co-chair of the Ontario Immunization Advisory Committee. PR has received investigator-initiated research grants to his institution from MSD and has received institutional funding from GlaxoSmithKline for local and international lectures and from AstraZeneca, GlaxoSmithKline, MSD, Sanofi, and Pfizer for participation in advisory boards. RTS has received payment or honoraria for lectures for AstraZeneca, Pfizer, and Sanofi Pasteur. CV has received payment or honoraria for lectures from AstraZeneca. LJB has not received personal fees or other personal benefits from pharmaceutical companies. His institution, University Medical Center Utrecht (UMCU), has received major funding (>€100 000 per industrial partner) from AbbVie, AstraZeneca, Sanofi, Janssen, Pfizer, MSD, and MeMed Diagnostics for investigator-initiated studies. UMCU has received major funding for the RSV-GOLD study from the Bill & Melinda Gates Foundation. UMCU has received major funding as part of the public private partnership IMI-funded RESCEU and PROMISE projects with partners GlaxoSmithKline, Novavax, Janssen, AstraZeneca, Pfizer, and Sanofi Pasteur. UMCU has received major funding by Julius Clinical for participating in clinical studies sponsored by AstraZeneca and Pfizer. UMCU has received minor funding (€1 000–25 000 per industrial partner) for consultation and invited lectures by AbbVie, AstraZeneca, Ablynx, Bavaria Nordic, MabXience, GlaxoSmithKline, Novavax, Pfizer, Moderna, AstraZeneca, MSD, Sanofi, Genzyme, and Janssen. LJB is the founding chairman of the ReSViNET Foundation. All other authors declare no competing interests., (Copyright © 2023 Elsevier Ltd. All rights reserved.)