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Pathogen-pathogen interactions represent a critical but little-understood feature of infectious disease dynamics. In particular, experimental evidence suggests that influenza virus and respiratory syncytial virus (RSV) compete with each other, such that infection with one confers temporary protection against the other. However, such interactions are challenging to study using common epidemiologic methods. Here, we use a mathematical modeling approach, in conjunction with detailed surveillance data from Hong Kong and Canada, to infer the strength and duration of the interaction between influenza and RSV. Based on our estimates, we further utilize our model to evaluate the potential conflicting effects of live attenuated influenza vaccines (LAIV) on RSV burden. We find evidence of a moderate to strong, negative, bidirectional interaction, such that infection with either virus yields 40-100% protection against infection with the other for one to five months. Assuming that LAIV reduces RSV susceptibility in a similar manner, we predict that the impact of such a vaccine at the population level would likely depend greatly on underlying viral circulation patterns. More broadly, we highlight the utility of mathematical models as a tool to characterize pathogen-pathogen interactions., Competing Interests: Competing interests: M.D.d.C. received postdoctoral funding (2017–2019) from Pfizer and consulting fees from GSK. The remaining authors declare no competing interests., (© 2024. The Author(s).)

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.)

Objective: To explore the clinical profile and outcomes in neonates hospitalized with respiratory syncytial virus (RSV) infection., Methods: Clinical features, respiratory support, pharmacological treatment, complications and outcomes of neonates admitted to the neonatal intensive care unit with RSV infection between January 2018 and March 2023 were recorded. Descriptive statistics were employed for analysis., Results: Thirty-seven neonates with RSV infection were analyzed. The most common presenting features were cough (n = 29, 74.4%), refusal to feed (n = 29, 74.4%) and apnea (n = 7, 17.9%). 19 (48.7%) neonates were mechanically ventilated, 28 (71.8%) required non-invasive respiratory support and 13 (35.1%) required bronchodilator therapy. All neonates were discharged after a median (IQR) duration of 14 (9, 23.5) days., Conclusion: Neonates with RSV infection requiring hospitalization have considerable respiratory morbidity requiring prolonged respiratory support and pharmacological therapy.

Older age and comorbid conditions increase risk for severe for respiratory syncytial virus (RSV). Skilled nursing facilities (SNFs) and assisted living (AL) facilities represent an intersection of risk factors. In a 3-year prospective study in Rochester, New York, we compared the population-based incidence of RSV-associated hospitalization for community-dwelling (CD), SNF, and AL adults aged ≥65 years. Their median ages were 76, 83 and 86 years, respectively, and dementia and congestive heart failure (CHF) were more prevalent among SNF and AL residents. The average annual incidences were 117 (95% confidence interval, 104-132), 440 (307-629) and 740 per 100 000 persons (523-1045), respectively, for CD, SNF, and AL adults aged ≥65 years, demonstrating a need for unequivocal RSV vaccine recommendations in SNF and AL residents., Competing Interests: Potential conflicts of interest. A. R. B. reports grant funding from Moderna, Cyanvac, Pfizer, Vaccitech, and Merck and serves as a consultant for Novavax, Sanofi, Merck, and GlaxoSmithKline. A. R. F. reports grant funding from Moderna, AstraZeneca, Cyanvac, Pfizer, and Vaccitech and serves as a consultant for GlaxoSmithKline, Moderna, Merck, and AstraZeneca. L. F. was an employee of Merck Sharp & Dohme, a subsidiary of Merck & Co, when the study was conducted. E. E. W. reports grant funding from Moderna, AstraZeneca, Cyanvac, Pfizer, Merck, and Vaccitech and serves as a consultant for GlaxoSmithKline, Moderna, Pfizer, Merck, and AstraZeneca. 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.)

Background: Respiratory syncytial virus (RSV) infection is gaining interest due to the recent development of vaccines but is still misdiagnosed in the elderly. The primary objective was to compare all-cause mortality at day 30. Secondary objectives were to compare clinical presentation and rates of consolidative pneumonia, hospitalization, and intensive care unit (ICU) admission., Methods: A single-center retrospective study was conducted in a French university hospital during 7 epidemic seasons including 558 patients aged ≥75 years: 125 with RSV and 433 with influenza (median age, 84.8 years)., Results: Patients with RSV had more respiratory symptoms (wheezing, dyspnea) whereas patients with influenza had more general symptoms (fever, asthenia, myalgia). The following were higher in the RSV group: consolidative pneumonia (28.8% vs 17.2%, P = .004), hospitalization (83.2% vs 70%, P = .003), ICU admission (7.2% vs 3.0%, P = .034), and length of stay (median [IQR], 9 days [2-16] vs 5 days [0-12]; P = .002). Mortality rates at day 30 were comparable (9.6% vs 9.7%, P = .973)., Conclusions: This study included the largest cohort of patients infected with RSV aged >75 years documented in-depth thus far. RSV shares a comparable mortality rate with influenza but is associated with higher rates of consolidative pneumonia, hospitalization, ICU admissions, and extended hospital stays., Competing Interests: Potential conflicts of interest. Authors C. Recto, H. Diakonoff, C. Donadio, L. Pouga, C. de Tymowski, and C. Kassasseya declare no conflicts of interest. S. Fourati received consulting fees from Spikimm, AstraZeneca, GSK, Pfizer, Moderna, and Cepheid, and has received lecture fees from AstraZeneca, GSK, Pfizer, Moderna, and Cepheid. J-M. Pawlotsky received consulting fees from Abbott, AbbVie, and GSK, and has received lecture fees from AbbVie and Gilead. N. de Prost received consulting fees from AstraZeneca, and has received lecture fees from Moderna. 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 commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Respiratory syncytial virus (RSV) is a leading cause of hospitalization among young children. Historically, American Indian and Alaska Native (AI/AN) children have experienced high rates of RSV-associated hospitalization. In August 2023, a preventive monoclonal antibody (nirsevimab) was recommended for all infants aged <8 months (born during or entering their first RSV season) and for children aged 8-19 months (entering their second RSV season) who have increased risk for severe RSV illness, including all AI/AN children. This evaluation in Alaska's Yukon-Kuskokwim Delta region estimated nirsevimab effectiveness among AI/AN children in their first or second RSV seasons during 2023-2024. Among 472 children with medically attended acute respiratory illness (ARI), 48% overall had received nirsevimab ≥7 days earlier (median = 91 days before the ARI-related visit). For children in their first RSV season (292), nirsevimab effectiveness was 76% (95% CI = 42%-90%) against medically attended RSV illness and 89% (95% CI = 32%-98%) against RSV hospitalization. For children in their second RSV season (180), effectiveness against medically attended RSV illness was 88% (95% CI = 48%-97%). Nirsevimab is effective for preventing severe RSV illness among infants entering their first RSV season and children entering their second season with increased risk for severe RSV, including all AI/AN children., Competing Interests: All authors have completed and submitted the International Committee of Medical Journal Editors form for disclosure of potential conflicts of interest. James W. Keck reports grant support from the National Institutes of Health (NIH) for the Alaska Native Center for Health Research Project and for the Wastewater Assessment for Coronavirus in Kentucky: Implementing Enhanced Surveillance Technology; from the National Science Foundation for the Pandemic Environmental Surveillance Center for Assessing Pathogen Emergency Project; from NIH for the COVID-19 infection and diabetes incidence in Native American People project; from NIH for the Neqkiuryaraq – The Art of Preparing Food Project; from Greenwall Foundation for the developing stakeholder-engaged ethical guidance for public health wastewater surveillance project service; and as safety officer and chair of the Data Safety Monitoring Board for National Institute of Diabetes and Digestive and Kidney Diseases-funded study: Enhancing the Diabetes Prevention Program. No other potential conflicts of interest were disclosed.

Background: Respiratory syncytial virus (RSV) prophylaxis using palivizumab effectively reduces RSV-associated morbidity in preterm infants. In Korea, national insurance coverage for palivizumab was implemented in October 2016 for moderate-to-late preterm (MLPT) infants born during the RSV season (October-March) who have older siblings. However, no large-scale studies have investigated the changes in the incidence and risk of severe acute lower respiratory infections (ALRIs) after insurance coverage implementation for MLPT infants., Methods: This large-scale retrospective cohort study used data from the Korean National Health Insurance Service between October 2013 and December 2019. MLPT infants (32 0/7-35 6/7 weeks of gestation) with older siblings were stratified into pre-insurance period (PIP; October 2013-September 2016) and insurance period (IP; October 2016-March 2019) groups based on the date of birth with respect to initial insurance palivizumab implementation. Severe ALRI outcomes (hospitalization, respiratory support, and intensive care unit admission) were evaluated up to 1 year of age using multivariable logistic regression models., Results: Of the 11,722 MLPT infants included in the study, 6,716 and 5,006 infants were included in the IP and PIP groups, respectively. The incidences of ALRI-hospitalization and ALRI-respiratory support were significantly lower in the IP group than that in PIP group (24.0% vs. 26.0% and 3.1% vs. 4.0%, respectively). Additionally, ALRI-respiratory support risk was significantly lower in the IP group (adjusted odds ratio 0.771, 95% confidence interval 0.626-0.949, P = 0.014) than that in the PIP group. Among infants born during the RSV season, the risk of ALRI-hospitalization and ALRI-respiratory support were significantly lower in the IP group than that in the PIP group. However, no significant differences were observed between the IP and PIP groups for infants born during the non-RSV season., Conclusion: The risks of severe ALRI outcomes decreased in Korea following the 2016 insurance implementation of palivizumab prophylaxis for MLPT infants born during the RSV season with older siblings., Competing Interests: The authors have no potential conflicts of interest to disclose., (© 2024 The Korean Academy of Medical Sciences.)

Human respiratory syncytial virus (RSV) is a major cause of acute respiratory infection. In 2020, RSV was eliminated from New Zealand due to non-pharmaceutical interventions (NPI) used to control the spread of SARS-CoV-2. However, in 2021, following a brief quarantine-free travel agreement with Australia, there was a large-scale nationwide outbreak of RSV that led to reported cases more than five-times higher than typical seasonal patterns. We generated 1470 viral genomes of both RSV-A and RSV-B sampled between 2015-2022 from across New Zealand. Using a phylodynamics approach, we used these data to better understand RSV transmission patterns in New Zealand prior to 2020, and how RSV became re-established in the community following the relaxation of COVID-19 restrictions. We found that in 2021, there was a large epidemic of RSV due to an increase in importations, leading to several large genomic clusters of both RSV-A ON1 and RSV-B BA9 genotypes. However, while a number of viral importations were detected, there was also a major reduction in RSV genetic diversity compared to pre-pandemic years. These data reveal the impact of NPI used during the COVID-19 pandemic on other respiratory infections and highlight the important insights that can be gained from viral genomes., Competing Interests: Competing interests The authors declare no competing interests., (© 2024. The Author(s).)

Background: Severe acute respiratory infection (SARI) is a major cause for hospital admission and associated with high mortality among children worldwide. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), influenza viruses and respiratory syncytial virus (RSV) are the most frequently identified pathogens in children with SARI. The duration of care can be affected by the type of infection and patient characteristics. Therefore, the objective of this study was to identify factors affecting the length of hospitalization in children infected with SARS-CoV-2, influenza A and RSV., Methods: We collected data on 713 children with SARI from the medical databases of a university hospital in Hungary. To examine whether there is a difference in the length of hospitalization in children with the SARI Kruskal-Wallis test was performed. To determine the factors that may have an impact on the duration of care a multiple logistic regression analysis was executed., Results: Our results showed that among RSV infected patients the proportions of children requiring intensive care (8.94%), mechanical ventilation (8.94%) and oxygen therapy (13.01%) and suffering from pneumonia (29.27%) were larger than among cases with SARS-CoV-2 and influenza A infection. Considering the age distribution and the duration of care in children with SARI, cases with RSV were significantly younger (p < 0.001) and stayed longer in the hospital (median: 5 days, IQR: 4-7 days, p < 0.001) than those with SARS-CoV-2 and influenza A virus. Multiple logistic regression analysis showed that RSV infection (adjusted odds ratio (aOR): 3.25, 95% confidence interval (CI): 1.43-7.38; p = 0.005), pneumonia (aOR: 3.65, 95% CI: 2.14-6.24; p < 0.001), mechanical ventilation or oxygen therapy (aOR: 3.23, 95% CI: 1.29-8.11; p = 0.012) and underlying illnesses (aOR: 2.39, 95% CI: 1.35-4.23; p = 0.003) significantly increased the odds of hospitalization for more than 4 days., Conclusions: Our research showed that of the viruses causing SARI, RSV had the greatest clinical relevance, contributing to hospital stays of more than 4 days in a large share of paediatric patients below 1 year of age. Our results supply new information on children with SARI, and provide evidence for health policy makers to allocate additional resources to hospitals during SARI epidemics., (© 2024. The Author(s).)

Background: With the increased availability of licensed vaccines for respiratory viruses such as severe acute respiratory syndrome coronavirus 2, respiratory syncytial virus (RSV), and influenza virus, a better understanding of the viral aetiology of severe acute respiratory infections (SARI) among children could help in optimising the use of these vaccines. We conducted a study among children aged <5 years hospitalised with SARI at a tertiary care children's hospital in north India and tested for common respiratory pathogens., Methods: We randomly enrolled eligible SARI cases aged <5 years from August 2013 to July 2015. SARI cases were defined as either <7-day history of fever with cough or in children aged eight days to three months, a physician diagnosis of acute lower respiratory infection requiring hospitalisation. We also enrolled an age-group matched control without any acute illness in a 2:1 ratio from the outpatient clinic within 24 hours of case enrolment. Nasopharyngeal and/or oropharyngeal swabs were collected and tested using TaqMan Array Cards, a real-time reverse transcription polymerase chain reaction-based multi-pathogen testing platform for selected respiratory viruses among the enrolled cases and controls. We compared the prevalence of each pathogen among cases and controls using the χ 2 (χ 2 ) or Fisher exact test (P < 0.05). We used logistic regression to estimate adjusted odds ratios (aORs) which were then used to calculate aetiologic fractions (EFs)., Results: We enrolled 840 cases and 419 outpatient controls. Almost half of the individuals in the whole sample were aged <6 months (n = 521, 41.4%). Females made up 33.7% of cases and 37.2% of controls. Viral detections were more common among cases (69%, 95% confidence interval (CI) = 66, 73) compared to controls (33%; 95% CI = 29, 38) (P < 0.01). RSV (n = 257, 31%; 95% CI = 28, 34%) was the most common virus detected among cases. Influenza A was detected among 24 (3%; 95% CI = 2, 4%), and influenza B among 5 (1%; 95% CI = 0, 1%) cases. The association between the virus and SARI was strongest for RSV (aOR = 23; 95% CI = 12, 47; EF = 96%). Antivirals were administered to 1% of SARI cases while 78% received antibiotics., Conclusions: Using a multi-pathogen molecular detection method, we detected respiratory viruses among more than two-thirds of children aged <5 years admitted with SARI in the Delhi tertiary care children's hospital. The guidelines for preventing and managing SARI cases among children could be optimised further with the improved availability of antivirals and vaccines., Competing Interests: Disclosure of interest: The authors completed the ICMJE Disclosure of Interest Form (available upon request from the corresponding author) and disclose no relevant interest., (Copyright © 2024 by the Journal of Global Health. All rights reserved.)

Importance: Respiratory syncytial virus (RSV) is a leading cause of acute respiratory tract infections among adults and is estimated to cause approximately 159 000 hospitalizations among adults aged 65 years and older in the US each year. Estimates of hospitalization among adults with outpatient medically attended RSV (MA-RSV) infections are required to design interventional studies that aim to prevent hospitalization., Objective: To assess absolute risk of 28-day, all-cause hospitalization following outpatient MA-RSV infections in adults., Design, Setting, and Participants: In this cohort study, data from 3 different deidentified databases containing electronic health records (EHR) linked to closed claims data (Optum's deidentified Integrated Claims-Clinical dataset, TriNetX Linked, and Veradigm Network EHR [VNEHR] database linked with claims) were analyzed separately across 6 RSV years (October 1, 2016, to September 30, 2022) in adults with commercial or government insurance. Outpatient (eg, clinics and emergency departments) MA-RSV infections were identified based on clinical laboratory data or RSV-specific International Statistical Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10-CM) diagnosis codes. Data were analyzed from March 2023 to April 2024., Main Outcomes and Measures: The main outcome was all-cause 28-day hospitalization following outpatient MA-RSV infections among all adults and a high-risk subgroup (defined as age ≥65 years or with asthma, chronic obstructive pulmonary disease [COPD], or congestive heart failure [CHF])., Results: In this cohort study of 67 239 MA-RSV infections in adults (2771 from Optum, 7442 from TriNetX, and 57 026 from VNEHR), most occurred among females (62%-67%) and comorbidity prevalences were 20.0% to 30.5% for COPD, 14.6% to 24.4% for CHF, 14.6% to 24.4% for asthma; 14.0% to 54.5% of individuals were aged 65 years or older. The proportion hospitalized was 6.2% (95% CI, 5.3%-7.1%) in Optum, 6.0% (95% CI, 5.4% to 6.5%) in TriNetX, and 4.5% (95% CI, 4.3%-4.6%) in VNEHR. Among the high-risk subgroup, the proportion hospitalized was 7.6% (95% CI, 6.5%-8.9%) in Optum, 8.5% (95% CI, 7.6%-9.4%) in TriNetX, and 6.5% (95% CI, 6.2%-6.8%) in VNEHR., Conclusions and Relevance: In this cohort study of adults with outpatient MA-RSV infections from 3 large deidentified US databases across 6 RSV seasons, approximately 1 in 20 adults experienced all-cause hospitalization within 28 days. The results of this study highlight the public health need for RSV prevention and treatment.

Importance: Respiratory syncytial virus (RSV) infection can cause severe illness in adults. However, there is considerable uncertainty in the burden of RSV-associated hospitalizations among adults prior to RSV vaccine introduction., Objective: To describe the demographic characteristics of adults hospitalized with laboratory-confirmed RSV and to estimate annual rates and numbers of RSV-associated hospitalizations, intensive care unit (ICU) admissions, and in-hospital deaths., Design, Setting, and Participants: This cross-sectional study used data from the RSV Hospitalization Surveillance Network (RSV-NET), a population-based surveillance platform that captures RSV-associated hospitalizations in 58 counties in 12 states, covering approximately 8% of the US population. The study period spanned 7 surveillance seasons from 2016-2017 through 2022-2023. Included cases from RSV-NET were nonpregnant hospitalized adults aged 18 years or older residing in the surveillance catchment area and with a positive RSV test result., Exposure: Laboratory-confirmed RSV-associated hospitalization, defined as a positive RSV test result within 14 days before or during hospitalization., Main Outcomes and Measures: Hospitalization rates per 100 000 adult population, stratified by age group. After adjusting for test sensitivity and undertesting for RSV in adults hospitalized with acute respiratory illnesses, rates were extrapolated to the US population to estimate annual numbers of RSV-associated hospitalizations. Clinical outcome data were used to estimate RSV-associated ICU admissions and in-hospital deaths., Results: From the 2016 to 2017 through the 2022 to 2023 RSV seasons, there were 16 575 RSV-associated hospitalizations in adults (median [IQR] age, 70 [58-81] years; 9641 females [58.2%]). Excluding the 2020 to 2021 and the 2021 to 2022 seasons, when the COVID-19 pandemic affected RSV circulation, hospitalization rates ranged from 48.9 (95% CI, 33.4-91.5) per 100 000 adults in 2016 to 2017 to 76.2 (95% CI, 55.2-122.7) per 100 000 adults in 2017 to 2018. Rates were lowest among adults aged 18 to 49 years (8.6 [95% CI, 5.7-16.8] per 100 000 adults in 2016-2017 to 13.1 [95% CI, 11.0-16.1] per 100 000 adults in 2022-2023) and highest among adults 75 years or older (244.7 [95% CI, 207.9-297.3] per 100 000 adults in 2022-2023 to 411.4 [95% CI, 292.1-695.4] per 100 000 adults in 2017-2018). Annual hospitalization estimates ranged from 123 000 (95% CI, 84 000-230 000) in 2016 to 2017 to 193 000 (95% CI, 140 000-311 000) in 2017 to 2018. Annual ICU admission estimates ranged from 24 400 (95% CI, 16 700-44 800) to 34 900 (95% CI, 25 500-55 600) for the same seasons. Estimated annual in-hospital deaths ranged from 4680 (95% CI, 3570-6820) in 2018 to 2019 to 8620 (95% CI, 6220-14 090) in 2017 to 2018. Adults 75 years or older accounted for 45.6% (range, 43.1%-48.8%) of all RSV-associated hospitalizations, 38.6% (range, 36.7%-41.0%) of all ICU admissions, and 58.7% (range, 51.9%-67.1%) of all in-hospital deaths., Conclusions and Relevance: In this cross-sectional study of adults hospitalized with RSV before the 2023 introduction of RSV vaccines, RSV was associated with substantial burden of hospitalizations, ICU admissions, and in-hospital deaths in adults, with the highest rates occurring in adults 75 years or older. Increasing RSV vaccination of older adults has the potential to reduce associated hospitalizations and severe clinical outcomes.

We looked at the interactions between viral loads, coinfection rates and disease severity for children infected with two pneumoviruses: human metapneumovirus (HMPV) and respiratory syncytial virus (RSV). The HMPV RNA load in nasopharyngeal swabs of hospitalized children was significantly higher in mono-infections compared to coinfections but this was not the case for RSV, which could be explained by different innate immune responses. Also, the viral load of neither of the two viruses was associated with disease severity although RSV-infected children had higher severity scores than HMPV-infected children., (© 2024 Wiley Periodicals LLC.)

Epidemiology of respiratory syncytial virus (RSV) bronchiolitis in the tropics is poorly understood, complicating the effective management of RSV epidemics. The main objective was to describe the seasonality of RSV bronchiolitis epidemics and the clinical characteristics of hospitalized infants over a 13-year period on the French Caribbean island of Martinique. Single-center retrospective observational study including infants under 2 years of age hospitalized at the Martinique University Hospital for RSV-positive bronchiolitis from January 2007 to December 2019. One thousand two hundred thirty-tree cases were included. Epidemics occurred during the rainy season, beginning in September, peaking in October/November and ending in December. A distinct biennial seasonality pattern was observed, with alternating years of high and low incidence. Mean duration of epidemics was of 11 weeks. Clinical characteristics of patients were similar to those hospitalized in temperate areas. Median hospital stay was 4 days. Median age was 3 months, 14.1% of patients were born prematurely, 2.5% had congenital heart disease and 41.1% required oxygen therapy. In Martinique, RSV bronchiolitis epidemics in infants occur in a regular biennial pattern during the rainy season. An accurate knowledge of the local seasonality will allow us to better anticipate hospital organization before epidemics., (© 2024 The Author(s). Journal of Medical Virology published by Wiley Periodicals LLC.)

Objective: RSV bronchiolitis is a leading cause of hospitalization in infants and young children. We aimed to document the economic burden and epidemiology of RSV over seven seasons in Southern Austria., Patients and Methods: All RSV-associated hospitalized (PCR-proven) children ≤ 5 years of age between 1 October 2015 and 30 April 2022 were collected retrospectively. Demographic and epidemiologic data, along with hospitalization costs (direct and indirect), were calculated., Results: Among 976 children hospitalized due to RSV infection, 87% were healthy term infants, and 79% were < 12 months old. Prematurity (13%) and pre-existing conditions (11%) significantly impacted older children-59% of cases in the 2nd compared with 68% in the 1st year of live. RSV-related hospital costs were approximately €2.0 millions per year (of a total of 60 millions per year). RSV accounted for 19% of hospitalizations due to acute respiratory illness (ARI) in children ≤ 5 years, 37% of all ARI < 6 months, 28% of all ARI < 12 and 6.3% of all-cause hospitalizations < 12 months of age, respectively., Conclusions: Every 5th hospitalization due to respiratory illness in children ≤ 5 years of age was associated with RSV, representing 7.9% of all hospitalizations and 3.3% of all paediatric hospitalization costs., (© 2024 The Author(s). Influenza and Other Respiratory Viruses published by John Wiley & Sons Ltd.)

Respiratory syncytial virus (RSV) represents a significant burden on older adults (aged ≥ 50 years) globally and can lead to acute respiratory tract infections with substantial morbidity and mortality. However, there is a significant gap in knowledge regarding RSV infection in older adults, particularly in the Asia-Pacific region. This knowledge gap underscores the need for targeted and comprehensive studies to fully understand the nuanced epidemiology of RSV in ageing populations. This review synthesises data from various countries, emphasising the impact of RSV on older populations in the Asia-Pacific region. The overall proportions of RSV-related ARIs among older patients ranged from 0.2% to 5.6%. Among older adult patients with CAP, RSV accounted for 1.1%-10.3% of cases. However, it is crucial to note that the diversity in reported percentages highlights the influence of factors such as geographic location, health care settings and diagnostic practices. The most common symptoms observed in older adults with RSV infection were cough, sputum production and fever, followed by dyspnoea, sore throat and rhinorrhoea. Most of the old adults with RSV infection had underlying diseases, and RSV can cause significant morbidity and mortality in old adults. Treatment of RSV infections predominantly involve supportive care, with aerosolised ribavirin reserved for severe cases, especially immunocompromised patients. Emerging antiviral agents, including fusion and nucleoprotein inhibitors, offer promising avenues for future therapeutics. The recent approval of the bivalent RSV prefusion F protein-based vaccine for individuals aged 60 and older represents a milestone in preventive strategies. In conclusion, RSV infection remains a significant threat to older adults in the Asia-Pacific region, necessitating ongoing research and surveillance efforts. The recent vaccine approval marks a positive milestone, but further studies are crucial for refining prevention and treatment approaches., (© 2024 John Wiley & Sons Ltd.)

Background: Respiratory syncytial virus (RSV) is an important cause of acute lower respiratory infections worldwide, including Thailand. This study aimed to assess clinical and economic burdens of RSV infections across different age groups in Thailand., Method: A retrospective cohort study was conducted using data from a tertiary care hospital from 2014 to 2021. Patients who tested at least one positive RSV were included and stratified into five age groups (< 2, 2-5, 5-18, 18-65, and > 65 years). Healthcare resource utilization, direct medical costs, and clinical outcomes were analyzed with descriptive statistics. Generalized linear models with gamma distributions and log link were used to model cost outcomes. Costs were reported in 2021 US dollars (USD), with 1 USD = 31.98 Thai Baht., Results: A total of 2122 RSV-positive patients were identified, half of which (1097) were hospitalized. The median (interquartile range [IQR]) total hospitalization costs ranged from USD780 (IQR: USD488-USD1185) in those < 2 years to USD2231 (IQR: USD1250-USD4989) in those aged 65+ years. Case fatality rates among hospitalized patients also varied from 2.5% to 28.4% depending on age. Increased age, presence of comorbidities, and need for critical care were associated with higher hospitalization costs., Conclusion: Among RSV-positive patients, younger children experienced the greatest burden, but poorer outcomes were observed in older adults. Higher costs were associated with older age, comorbidities and critical care needs. Understanding RSV economic burdens is crucial for assessing the cost-effectiveness and public health value of vaccination programs that prioritize at-risk groups to mitigate the public health impact., (© 2024 The Author(s). Influenza and Other Respiratory Viruses published by John Wiley & Sons Ltd.)

We recently expanded the viral genomic surveillance program in Minnesota, USA, to include human respiratory syncytial virus. We performed whole-genome sequencing of 575 specimens collected at Minnesota healthcare facilities during July 2023-February 2024. Subgroups A and B differed in their genomic landscapes, and we identified 23 clusters of genetically identical genomes.

Almost 60 years after a disastrous clinical vaccine trial in children, which resulted in enhanced disease and even deaths, the world of RSV vaccination is currently undergoing a dramatic positive change and development, closely linked to advances in new vaccine technologies. Three licensed safe and highly efficacious vaccines, Abrysvo, Arexvy and mRESVIA, reduce the incidence of RSV lower respiratory disease by 80% in people older than 60 years of age. Questions regarding long-term protection and effectiveness in specific risk groups with chronic medical conditions remain, and furthermore, innovative and safe concepts to actively vaccinate pregnant women and infants to prevent severe RSV infections - also in these high-risk populations - are eagerly awaited.Passive vaccination with the long-acting monoclonal antibody Nirsevimab for prevention of severe disease in the first RSV season of infants is a major innovation in global health and the importance and benefits of reducing the number of intramuscular injections for high-risk children is immense. In the coming years, results of numerous pediatric candidate RSV vaccine studies are expected, although particular caution seems advisable for historical reasons. In summary, the field of RSV vaccination has been revolutionized in the last 2 years and we will see further significant progress soon., Competing Interests: Till Koch gibt an, dass kein Interessenkonflikt besteht. Robin Kobbe: Robin Kobbe ist Investigator in mRNA-Impfstoffstudien der Firma Moderna® und BioNTech/Pfizer®, für die sein Arbeitgeber Fördermittel von den jeweiligen Unternehmen erhält. Die genannten Studien sind nicht Teil der hier vorgestellten RSV Impfstoffe., (Thieme. All rights reserved.)

Objectives: Although human bocavirus (HBoV) is primarily linked to respiratory tract infections, its exact role as a respiratory pathogen remains unclear. This study aims to investigate HBoV detection rates, as well as clinical, laboratory, microbiological, and radiological characteristics, length of stay in the emergency department (ED), rate of hospitalization, and severity of illness in cases where HBoV is detected in respiratory secretions., Methods: We conducted a retrospective analysis of all consecutive patients under 18 years who visited a large-volume tertiary pediatric ED from January to December 2023 and tested positive for HBoV in their respiratory viral panel (RVP)., Results: Among the 14,315 patients who underwent RVP testing during the study period, 591 (4%) tested positive for HBoV. After excluding those with incomplete data, 528 patients (57% male) were included in the analyses. The median age was 2.8 [1.2-4.9] years. The most common symptoms were cough (67%), fever (58%), runny nose/nasal congestion/sore throat (34%), and respiratory distress (24%). Thirty percent of the patients had a history of antibiotic use before admission. Thirteen percent of the patients had at least one chronic illness. Co-infection with HBoV occurred in 37% of the patients, with respiratory syncytial virus (RSV) being the most frequently co-detected virus (45%). Lymphopenia was documented in 12% of patients, and 36% had elevated C-reactive protein levels (median 21 [12-38] g/dl). Abnormal chest X-rays were noted in 85% of patients. The management approach included outpatient care for more than half of the patients (69%). Clinical severity was classified as high in 11% of patients ( n  = 60), necessitating ICU admission., Conclusion: Although typically mild, HBoV infections can escalate to severe respiratory illnesses, requiring respiratory support and intensive care.

Introduction: Our aim was to estimate the risk of pneumonia, admission to intensive care unit (ICU) or death in individuals ≥65 years old admitted to hospital with RSV, compared to influenza or COVID-19., Methods: We included hospitalised patients from Severe Acute Respiratory Infection Surveillance in Spain between 2021-2024, aged ≥65 years, laboratory confirmed for RSV, influenza or SARS-CoV-2. Using a binomial regression with logarithmic link, we estimated the relative risk (RR) of pneumonia, ICU admission and in-hospital mortality, in patients with RSV compared to influenza or SARS-CoV-2, adjusting for age, sex, season and comorbidities. We stratified the estimates by vaccination status for influenza or SARS-CoV2., Results: Among patients unvaccinated for influenza or SARS-CoV-2, those with RSV had similar or lower risk of pneumonia [vs. influenza: RR= 0.91 (95% Confidence Interval: 0.72-1.16); vs. SARS-CoV-2: 0.81 (0.67-0.98)], ICU admission [vs. influenza: 0.93 (0.41-2.08); vs. SARS-CoV-2: 1.10 (0.61-1.99)] and mortality [vs. influenza: 0.64 (0.32-1.28); vs. SARS-CoV-2: 0.56 (0.30-1.04)]. Among the vaccinated, results were largely similar except for a higher risk of ICU admission with RSV [vs. influenza: 2.13(1.16-3.89); vs. SARS-CoV-2: 1.83 (1.02-3.28)] CONCLUSIONS: RSV presented similar or lower intrinsic severity than influenza or SARS-CoV2. Among vaccinated patients, RSV was associated to higher ICU-admission, suggesting the potential for preventive RSV vaccination., 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 Authors. Published by Elsevier Ltd.. All rights reserved.)

Introduction: Respiratory syncytial virus (RSV) is a common, highly contagious pathogen and a leading cause of serious illness among infants and older adults. While existing scientific evidence has predominantly focused on the epidemiology and disease burden of RSV in infants, data in older adults remain limited in some countries, including those in Southeast Asia (SEA) and the Middle East and North Africa (MENA) region. Here, we outline the key challenges for understanding the burden of RSV in older adults in SEA and the MENA region and we propose opportunities for improving understanding and eventually reducing the impact of RSV., Main Findings and Conclusions: A key challenge identified by the expert group, particularly in older adults, is a lack of awareness (among healthcare professionals, policy makers, and the public) of RSV burden and the associated risks for severe outcomes. This is often confounded by the complexities of underdiagnosis, surveillance limitations, and comorbidities. To address these issues, we suggest medical education initiatives for physicians in SEA and the MENA region to better understand the need to protect older adults from RSV, and encourage more widespread routine testing to better understand the burden of RSV. We also recommend surveillance studies in these regions to provide comprehensive and accurate epidemiological data on RSV in older adults. Finally, in the absence of current surveillance data in these regions, we propose extrapolating existing global data and local pediatric data to inform the likely burden of RSV in older adults. A graphical abstract is available with this article., (© 2024. GlaxoSmithKline Biologicals SA 2024.)

Objectives: To investigate seasonality, epidemiologic characteristics, and clinical severity variations of respiratory syncytial virus (RSV)-associated hospitalizations following the easing of COVID-19 restrictions in Tuscany, Italy, up to the 2022-2023 season., Methods: From 2017 to 2023, a dynamic cohort consisting of all resident children aged ≤2 years was followed up in regional registries. The person-time incidence rate of RSV-associated hospitalizations per 1,000 person-years and risk of severe hospitalization (intensive care unit, continuous positive airway pressure, or mechanical ventilation) per 100 RSV hospitalizations were calculated. RSV seasonality was investigated with retrospective methods., Results: A total of 193,244 children were followed up. After the easing of restrictions, RSV epidemics showed earlier seasonality and shorter duration compared with pre-pandemic (2017 to 2019), with this deviation decreased in 2022-2023. In 2021-2022 and 2022-2023, the incidence rate of RSV-associated hospitalizations significantly increased compared with pre-pandemic (2022-2023 risk ratio 3.6, 95% confidence interval 3.3-4.0), with larger increases among older age groups. Among hospitalized children, only those aged ≥12 months showed an increased risk of severe hospitalization, particularly during 2021-2022 (risk ratio 4.7, 95% confidence interval 1.5-24.3)., Conclusions: Our findings suggest a gradual return of RSV epidemics to the pre-pandemic pattern, although relevant increases in disease incidence persist. Reduced regular RSV exposure among older children may lead to declining immunity and increased severe outcome risks., Competing Interests: Declarations of competing interest The authors have no competing interests to declare., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Background: Severe acute respiratory syndrome related coronavirus (SARS-CoV-2) bronchiolitis has arisen with the SARS-CoV-2 pandemic. There is a paucity of literature on SARS-CoV-2 bronchiolitis., Objective: The purpose of our paper was to review and compare outcomes in bronchiolitis due to severe acute respiratory syndrome related coronavirus 2 (SARS- CoV-2) and Respiratory Syncytial Virus (RSV). We also performed a subgroup analysis of two disrupted RSV seasons during the pandemic., Methods: This was a retrospective study from a US TriNetX database from March 1, 2020-January 1, 2023. Propensity matching was utilized for confounders., Results: There was a total of 3,592 patients (1,796 in each group) after propensity matching. There was an increased risk of oxygen saturation ≤95 % (RR=1.50 95 % CI 1.58-1.94, p = 0.002) and ICU admission (RR=1.44 95 % CI 1.06-1.94, p = 0.02) in those with SARS- CoV-2 but not for oxygen saturation ≤90 % (RR=1.03 95 %CI 0.75-1.42, p = 0.85) or intubation (RR=0.73 95 % CI 0.35-1.47, p = 0.37). There was a decreased risk of a patient with SARS- CoV-2 bronchiolitis being hospitalized (RR=0.65 95 % CI 0.57-0.74, p < 0.0001), respiratory rate ≥60 (RR=0.64 95 % CI 0.48-0.88, p < 0.001) or ≥70 (RR=0.64 95 % CI 0.43-0.96, p = 0.03) when compared to RSV bronchiolitis. Specifically examining SARS- CoV-2 versus RSV bronchiolitis during the delayed RSV seasons, during the first season both infections were not severe, but during the second RSV bronchiolitis season, patients infected with RSV had less risk of ICU admission compared to those infected with SARS- CoV-2., Conclusion: SARS- CoV-2 bronchiolitis patients appeared to have more severe outcomes since the risk of ICU admission was higher for these patients. Also, during the second delayed RSV season, SARS- CoV-2 bronchiolitis was more severe than RSV bronchiolitis., Competing Interests: Declaration of competing interest By Heart and Lung, all authors are required to disclose any and all commercial, financial, and other relationships in any way related to the subject of this article as per ICMJE conflict of interest guidelines (see www.icmje.org). The authors declare no conflicts of interest., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Introduction: While respiratory syncytial virus (RSV) is one of the most common pathogens in adults admitted to the ICU due to respiratory diseases, no reports regarding the occurrence rate of RSV infections in adults in Japan during the COVID-19 pandemic exist., Patients and Methods: We conducted this retrospective study to examine the exact occurrence rate of RSV infections in adults. We reviewed all patients (≥18 years) with any respiratory symptoms who received quantitative polymerase chain reaction (PCR) using nasopharyngeal samples for respiratory viruses by GeneLEAD at the Aichi Medical University Hospital between November 2022 and November 2023., Results: A total of 541 adult patients who underwent PCR test were enrolled in this study. RSV was identified in 18 cases (3.3 %); 8 (1.5 %) upper and 10 (1.8 %) lower respiratory tract infections. Influenza A and SARS-CoV-2 were found in 10 (1.8 %) and 61 (11.3 %), respectively. Patients with RSV infections and COVID-19 had more comorbidities than those with Influenza virus infections. As for RSV-associated with lower respiratory tract infection cases, 10 developed acute respiratory failure, resulting in 1 fatal case due to pneumonia and 1 died of septic shock due to ileus. The 30-, 90-day mortality rates were 1 (6 %) and 2 (11 %) respectively., Conclusion: About 3 % of adults had RSV infections during the COVID-19 pandemic. The outcomes of RSV infections in adults were similar to those by COVID-19. Those with comorbidities should have a preventive method against RSV infections, the same as for COVID-19., Competing Interests: Declaration of competing interest The authors declare that they have no conflict of interest., (Copyright © 2024 Japanese Society of Chemotherapy, Japanese Association for Infectious Diseases, and Japanese Society for Infection Prevention and Control. Published by Elsevier Ltd. All rights reserved.)

Aim: To explore whether children in specialist care with COVID-19 have increased post-discharge health care use when compared with children in specialist care with 1) respiratory syncytial virus (RSV) infection, and 2) other respiratory tract infections (RTIs)., Methods: In 34,214 children aged 1 month to 5 years who were registered as having one or more hospital visit (outpatient or inpatient) with a diagnosis of COVID-19 ( N = 128), RSV infection ( N = 4,009), or other RTIs ( N = 34,458) from 2017 to 2021, we used a difference-in-differences study design to investigate individual all-cause primary and specialist health care use from 12 weeks prior to 12 weeks after the hospital visit, stratified by infants (1 to 11 months) and children (1 to 5 years)., Results: We found a slight increase in primary health care use in the first 4 weeks after the hospital visit for infants with COVID-19 when compared with infants with RSV infection (6 per 10,000; 95% CI [2, 13], a 0.52% relative increase). For infants diagnosed with COVID-19, we found a similar post-visit increase in inpatients when compared with infants with RSV infection, which lasted for 12 weeks., Conclusions: Our findings imply a slightly increased health care use among infants after a hospital visit for COVID-19 than among infants with other RTIs, the potential etiological mechanisms of which deserve future clinical research. Severe COVID-19 in young children will not represent any markedly increased burden on the health services ., Competing Interests: Declaration of conflicting interestsThe authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Background: Human respiratory syncytial virus (HRSV) is worldwide one of the leading causes of acute respiratory tract infections in young children and the elderly population. Two distinct subtypes of HRSV (A and B) and a multitude of genotypes have been described. The laboratory of Clinical and Epidemiological Virology (KU Leuven/University Hospitals Leuven) has a long-standing history of HRSV surveillance in Belgium., Methods: In this study, the seasonal circulation of HRSV in Belgium was monitored during 8 consecutive seasons prior to the SARS-CoV-2 pandemic (2011-2012 until 2018-2019). By use of a multiplex quantitative real time PCR panel, 27,386 respiratory samples were tested for HRSV. Further subtyping and sequencing of the HRSV positive samples was performed by PCR and Sanger sequencing. The prevalence and positivity rate were estimated in 4 distinct age groups and the circulating strains of each subtype were situated in a global context and in reference to the described genotypes in literature., Results: HRSV circulated in Belgium in a yearly re-occurring pattern during the winter months and both HRSV subtypes co-circulated simultaneously. All HRSV-B strains contained the 60 nt duplication in the HVR2 region of the G gene. Strains of subtype HRSV-A with a 72 nt duplication in the HVR2 region were first observed during the 2011-2012 season and replaced all other circulating strains from 2014 to 2015 onwards., (© 2024. The Author(s).)

Acute respiratory infections (ARIs) are the most common issue in pediatric clinical practice. They pose a significant public threat, with high morbidity and mortality rates worldwide. Aiming at understanding the epidemiological characteristics of respiratory pathogens and their risk factors among children in eastern Guangdong, China. Samples obtained from 15,993 children hospitalized with ARIs in eastern Guangdong Province were tested for 14 pathogens via multiplex polymerase chain reaction (PCR) from May 2019 to July 2023. The number of hospitalizations for ARIs was correlated with pathogens, age, meteorological parameters, and the pandemic of COVID-19. The data were analyzed by different statistical methods. Among all the samples, the positive rate with ARIs accounted for 68.94% (11,026/15,993) in hospitalized patients. Cytomegalovirus (CMV) (24.49%), Streptococcus pneumoniae (SP) (20.54%), and Respiratory Syncytial Virus (RSV) (14.16%) were the top three pathogens with the greatest infection rates. Among hospitalized patients, there were more single infections in pediatric patients (40.91%, P < 0.001). Compared with bacterial infection and mixed infection, the detection rate of virus infection was higher in pediatric (36.04%, P < 0.001). Age-related increases in Mycoplasma pneumoniae (MP) infection (r = 0.729, P < 0.001) and decreases in RSV infection were observed (r = 0.88, P < 0.001). The virus infection peaked at six months, and the bacterial infection and mixed infection peaked at 1-3 years. Viral pathogens are on the rise in the post-pandemic era. The prevalence of SP infection was more influenced by the Air Quality Index (AQI), RSV infections were more clearly influenced by temperature, and Influenza A virus (IAV) infections were more strongly correlated with both the AQI and relative humidity (P < 0.001). This study highlights the need of keeping an eye on monitoring meteorological factors in assessing hospitalizations for pediatric ARIs in eastern Guangdong, China, especially RSV- and SP-associated hospitalizations., (© 2024. The Author(s).)

Background: In addition to the persistence of SARS-CoV-2 infections, those with Influenza A/B and RSV have reappeared in 2022/23. To compare the development of prevalence, clinical outcomes and risk factors, we analysed data of the season 2023/24 from the same region/hospital as for 2022/23., Methods: Patients covering the whole age range with a positive polymerase chain reaction (PCR) test for SARS-CoV-2, Influenza A/B, RSV were included from the internal, neurological and paediatric units of the RoMed hospital Rosenheim, Germany/Bavaria, from August 1st 2023 to 29th February 2024., Results: Of 932 patients included, 912 showed single infections with SARS-CoV-2, Influenza A or RSV (47.9% female, median age 68.0 years; 52.9% SARS-CoV-2, 23.2% Influenza A, 21.8% RSV). Co-infections (2.0%) and Influenza B (0.1%) were negligible. In patients of age ≥ 18 years (n = 628, 68.5% SARS-CoV-2, 26.0% Influenza A, 5.6% RSV), patients with Influenza A were younger compared to SARS-CoV-2 (p < 0.001), with RSV similar to SARS-CoV-2. Heart failure and asthma were the most prevalent comorbidities for RSV, immunosuppression for Influenza A. Admission to Intensive Care Unit (ICU) occurred in 111 patients (17.0% of SARS-CoV-2, 17.2% Influenza A, 28.6% RSV), and 59 patients died (8.8% SARS-CoV-2, 8.6% Influenza A, 20.0% RSV). Low-flow oxygen supplementation and non-invasive ventilation (NIV) were most frequent for RSV (68.6% and 20.0%, respectively), oxygen demand upon admission for Influenza A (39.3%), without differences in high-flow oxygen supply or length of hospital stay. Among patients aged < 18 years (n = 284, 21.4% SARS-CoV-2, 18.0% Influenza A, 57.1% RSV), 15 were admitted to ICU (4.8% SARS-CoV-2, 3.8% Influenza A, 6.0% RSV); none of them died. Oxygen supply via high-flow, low-flow or upon admission was highest for RSV (23.8%, 70.2%, 21.4%, respectively), as well as the length of hospital stay., Conclusion: Between 8/2023 to 2/2024, a large population of patients hospitalized due to respiratory tract infection, showed relative contributions of SARS-CoV-2, Influenza A or RSV similar to those in 2022/23. The findings underline that in both, adults and children, RSV posed a relatively higher clinical risk than Influenza A and SARS-CoV-2, though absolute numbers remained highest for SARS-CoV-2., (© 2024. The Author(s).)

Background: Respiratory syncytial virus vaccines first recommended for use during 2023 were efficacious against lower respiratory tract disease in clinical trials. Limited real-world data regarding respiratory syncytial virus vaccine effectiveness are available. To inform vaccine policy and address gaps in evidence from the clinical trials, we aimed to assess the effectiveness against respiratory syncytial virus-associated hospitalisations and emergency department encounters among adults aged at least 60 years., Methods: We conducted a test-negative design analysis in an electronic health records-based network in eight states in the USA, including hospitalisations and emergency department encounters with respiratory syncytial virus-like illness among adults aged at least 60 years who underwent respiratory syncytial virus testing from Oct 1, 2023, to March 31, 2024. Respiratory syncytial virus vaccination status at the time of the encounter was derived from electronic health record documentation, state and city immunisation registries, and, for some sites, medical claims. Vaccine effectiveness was estimated by immunocompromise status, comparing the odds of vaccination among respiratory syncytial virus-positive case patients and respiratory syncytial virus-negative control patients, and adjusting for age, race and ethnicity, sex, calendar day, social vulnerability index, number of underlying non-respiratory medical conditions, presence of respiratory underlying medical conditions, and geographical region., Findings: Among 28 271 hospitalisations for respiratory syncytial virus-like illness among adults aged at least 60 years without immunocompromising conditions, vaccine effectiveness was 80% (95% CI 71-85) against respiratory syncytial virus-associated hospitalisations, and vaccine effectiveness was 81% (52-92) against respiratory syncytial virus-associated critical illness (ICU admission or death, or both). Among 8435 hospitalisations for respiratory syncytial virus-like illness among adults with immunocompromising conditions, vaccine effectiveness was 73% (48-85) against associated hospitalisation. Among 36 521 emergency department encounters for respiratory syncytial virus-like illness among adults aged at least 60 years without an immunocompromising condition, vaccine effectiveness was 77% (70-83) against respiratory syncytial virus-associated emergency department encounters. Vaccine effectiveness estimates were similar by age group and product type., Interpretation: Respiratory syncytial virus vaccination was effective in preventing respiratory syncytial virus-associated hospitalisations and emergency department encounters among adults aged at least 60 years in the USA during the 2023-24 respiratory syncytial virus season, which was the first season after respiratory syncytial virus vaccine was approved., Funding: The Centers for Disease Control and Prevention., Competing Interests: Declaration of interests NPK reports support for other work from Sanofi Pasteur, Merck, Pfizer, Seqirus, and GSK, unpaid expert panel membership for a planned hepatitis E phase 2 vaccine clinical trial among pregnant women in Pakistan, and unpaid membership on the Western States COVID-19 Scientific Safety Review Workgroup, Board on Population Health and Public Health Practice, National Academies of Science, Engineering, and Medicine, and National Vaccine Advisory Committee Safety Subcommittee. SJG reports funding from the National Institutes of Health's National Center for Advancing Translation Sciences and National Institute of Mental Health. TCO reports consulting fees from Regenstrief Institute as a domain expert in patient matching in global health informatics, travel support from Regenstrief Institute and Patient-Centered Outcomes Research institute, and holds a patent (patent number PCT/US2018/047961). MBD, BED, and WFF report an additional CDC contract for the Vaccine Safety Datalink. TS reports unpaid participation as a member of the Advisory Committee on the Immunization Practices Influenza Vaccine Work Group, is chief of the Utah Adult Immunization Coalition, and is a member of the Utah Department of Health and Human Services Scientific Advisory Committee on Vaccines. OZ reports funding from the National Institute of Allergy and Infectious Diseases (grant number R01AI168373). NPK, JT, and KG report a CDC contract for VISION (contract number 75D30123C17595). SR reports funding from Biofire and GSK. MB reports speaker bureau participation for Innoviva Specialty Therapeutics. CEM reports funding from AstraZeneca, GSK, National Institutes of Health, US Department of Defense, and Patient-Centered Outcomes Research Institute, payment or honoraria for a lecture from Pri-Med, and leadership on the American Lung Association of Minnesota board, the Minnesota Department of Health Long COVID Advisory Committee, and on the Minnesota Department of Health Asthma Care Advisory Committee. JAW, PKM, SWB, SER, and EAKR report a CDC contract for VISION (contract number 75D30121D12779). KD, SAI, SJG, TCO, MBD, KN, BED, WFF, CR, KSA, and CEM report payments made to their institution by CDC via Westat. All other authors declare no competing interests., (Copyright © 2024 Published by 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.)

Background/Objective: Respiratory syncytial virus (RSV) is a major cause of bronchiolitis in infants and young children. Bronchiolitis, an acute inflammation of the lower respiratory tract, can lead to pneumonia, respiratory failure, and death. We aimed to compare the incidence and severity of RSV infection in children aged 0-60 months before and during the coronavirus disease 2019 (COVID-19) pandemic. Methods: A retrospective chart review was conducted on patients aged 0-60 months who tested positive for RSV between May 1, 2018, and May 31, 2022, in a community hospital in Queens County, New York City, United States. Comparisons were made between seasons 2018-2019 and 2019-2020 as before, and seasons 2020-2021 and 2021-2022 as during the COVID-19 pandemic. Severity of RSV infection was assessed using the Bronchiolitis Severity Score (BSS). Data were analyzed using R software, a p value of < 0.05 was considered statistically significant. Results: The incidence of RSV infection in seasons 2018-2019 and 2019-2020 peaked from mid-October to February, whereas the first season during the COVID-19 pandemic (2020-2021) was truncated with a very low incidence of RSV infection, and season 2021-2022 peaked from September to January, with the highest incidence (37%) and lower frequency of RSV infection at any given point. Patients during the season 2021-2022 were older ( H  [2, 196.6] = 12.5, p < 0.001, 95% CI = [5.4, 25.6]) and had milder illness ( H  [2, 187.5] = 7.5, p < 0.01, 95% CI = [2.1, 19.2]). Conclusions: We observed a lower incidence of RSV infection and a lower rate of hospitalization for RSV during the COVID-19 pandemic. The second RSV season during the COVID-19 pandemic began earlier, lasted longer, and had a lower frequency. Older children with milder illnesses were affected most during this season. RSV epidemiology and disease burden were impacted by the COVID-19 pandemic and could have significant ramifications for its prevention and control strategies., Competing Interests: The authors declare no conflicts of interest., (Copyright © 2024 Jose Boris Trigueros Montes et al.)

Background: Recently, several novel RSV immunisation products that protect infants and older adults against RSV disease have been licensed in Europe. We estimated the effectiveness and efficiency of introducing these RSV immunisation strategies in Germany., Methods: We used a Bayesian framework to fit a deterministic age-structured dynamic transmission model of RSV to sentinel surveillance and RSV-specific hospitalisation data in Germany from 2015 to 2019. The calibrated model was used to evaluate different RSV intervention strategies over 5 years: long-acting, single-dose monoclonal antibodies (mAbs) in high-risk infants aged 1-5 months; long-acting mAbs in all infants aged 1-5 months; seasonal vaccination of pregnant women and one-time seasonal vaccination of older adults (75 + /65 + /55 + years). We performed sensitivity analysis on vaccine uptake, seasonal vs. year-round maternal vaccination, and the effect of under-ascertainment for older adults., Results: The model was able to match the various RSV datasets. Replacing the current short-acting mAB for high-risk infants with long-acting mAbs prevented 1.1% of RSV-specific hospitalisations in infants per year at the same uptake. Expanding the long-acting mAB programme to all infants prevented 39.3% of infant hospitalisations per year. Maternal vaccination required a larger number to be immunised to prevent one additional hospitalisation than a long-acting mAB for the same uptake. Vaccination of adults older than 75 years at an uptake of 40% in addition to Nirsevimab in all infants prevented an additional 4.5% of all RSV hospitalisations over 5 years, with substantial uncertainty in the correction for under-ascertainment of the RSV burden., Conclusions: Immunisation has the potential to reduce the RSV disease burden in Germany., (© 2024. The Author(s).)

Background: Respiratory Syncytial Virus (RSV) is a common cause of lower respiratory tract infections (LRTI) and hospitalization worldwide. The impact of RSV in Latin America and the Caribbean (LAC) including expensive treatment options, such as palivizumab, have been extensively discussed. However, publications on the impact of RSV disease burden in the region are scarce. This systematic review aimed to determine the incidence and prevalence of RSV in LAC by age and RSV subtype., Methods: We conducted a systematic review following Cochrane methods to evaluate the disease burden of RSV in LAC countries. We searched studies from January 2012 to January 2023 in literature databases and grey literature without language restrictions. We included guidelines, observational, economic, and surveillance studies from LAC countries. Pairs of reviewers independently selected, and extracted data from included studies. The risk of bias was assessed using the Study Quality Assessment Tools (NHLBI) and AGREE-II. We performed proportion meta-analyses using methods to stabilize the variance. The protocol was registered in PROSPERO (CRD42023393731)., Results: We included 156 studies, mainly from Brazil (25%), Colombia (14.5%), and Argentina (13.8%), as well as four clinical practice guidelines. Most studies were cross-sectional (76.9%) and were classified as low risk of bias (52.6%). The majority included inpatients (85.6%), pediatric (73.7%), and normal-risk patients (67.1%). The highest pooled prevalence was estimated in patients <1 year old (58%), with type A and B prevalence of 52 and 34%, respectively. The RSV-LRTI incidence was 15/100 symptomatic infants aged <2 years old, and the ICU admission was 42%. The RSV-LRTI lethality was 0.6, 3% in patients aged <2 and 0-5 years old, respectively, and 23% among >65 years old high-risk patients. The identified guidelines lack methodological rigor and have limitations in their applicability. The seasonality was more evident in South America than in Central America and The Caribbean, with a clear gap during the pandemic., Conclusion: This is the most exhaustive and updated body of evidence describing a significant burden of RSV in LAC, particularly at the extremes of life, and its seasonality patterns. Our findings could contribute could contribute facilitating effective prevention and treatment strategies for this significant public health problem., Systematic Review Registration: PROSPERO CRD UK (registration number: CRD42023393731)., Competing Interests: JL works for Vaccine Medical, Pfizer SAS, Bogotá, Colombia and RA works for Pfizer Inc., New York, New York, United States. RU-G has participated recently in scientific events sponsored by Pfizer and AstraZeneca, received honoraria as a speaker by Pfizer, and in advisory boards by MSD, all related to RSV prevention and treatment. 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. The author(s) declared that they were an editorial board member of Frontiers, at the time of submission. This had no impact on the peer review process and the final decision., (Copyright © 2024 Ciapponi, Palermo, Sandoval, Baumeister, Ruvinsky, Ulloa-Gutierrez, Stegelmann, Ruesjas, Cantos, LaRotta, de Almeida and Bardach.)

Respiratory syncytial virus (RSV) causes severe infections in infants, immunocompromised or elderly individuals resulting in annual epidemics of respiratory disease. Currently, limited clinical surveillance and the lack of predictable seasonal dynamics limit the public health response. Wastewater-based epidemiology (WBE) has recently been used globally as a key metric in determining prevalence of severe acute respiratory syndrome coronavirus 2 in the community, but its application to other respiratory viruses is limited. In this study, we present an integrated genomic WBE approach, applying reverse-transcription quantitative polymerase chain reaction and partial G-gene sequencing to track RSV levels and variants in the community. We report increasing detection of RSV in wastewater concomitant with increasing numbers of positive clinical cases. Analysis of wastewater-derived RSV sequences permitted identification of distinct circulating lineages within and between seasons. Altogether, our genomic WBE platform has the potential to complement ongoing global surveillance and aid the management of RSV by informing the timely deployment of pharmaceutical and nonpharmaceutical interventions., Competing Interests: Potential conflicts of interest . All authors: No reported 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.)

Background: Data on the true prevalence of respiratory syncytial virus (RSV) among medically attended acute respiratory illnesses (MAARI) has been limited by the lack of regular clinical testing of mild to moderate illnesses. Here we present a prospective evaluation of the epidemiology of RSV-associated MAARI across age groups and multimorbidity status over 3 seasons, which is informative in light of the recommendations for shared decision making for vaccination in older adults., Methods: Ambulatory patients ≥6 months of age meeting a common MAARI case definition were prospectively enrolled in the Michigan Ford Influenza Vaccine Effectiveness (MFIVE) study, a subsite of the US Influenza Vaccine Effectiveness Network. All participants were tested by nasal-throat swab for RSV and influenza, including subtype, independently from clinician-directed testing. Participant illness characteristics and calculated multimorbidity-weighted index (MWI) were collected by in-person survey and electronic medical record review., Results: Over 3 surveillance seasons (fall 2017 to spring 2020), 9.9% (n = 441) of 4442 participants had RSV detected. RSV-associated MAARI was more prevalent than influenza for participants 6 months to 4 years of age. Adults with RSV-MAARI had higher median MWI scores overall compared to influenza-MAARI and controls with neither virus (1.62, 0.40, and 0.64, respectively)., Conclusions: RSV is a significant, underrecognized cause of MAARI in both children and adults presenting for ambulatory care. Multimorbidity is an important contributor to RSV-associated MAARI in outpatient adults, providing information to support shared clinical decision making for vaccination., Competing Interests: Potential conflicts of interest. E. T. M. has received research funding from Merck related to the submitted work. L. L. has received consulting fees from Janssen paid to institution. 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 commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Background: Respiratory syncytial virus (RSV) is the leading cause of severe respiratory infections in infants worldwide, significantly affecting their health and contributing to the global healthcare burden. We aimed to examine healthcare resource utilisation patterns and costs for infants under one year old with confirmed RSV infection across subgroups of different gestational ages and health conditions and the cost implications of RSV infections over time, thereby demonstrating the economic burden of the disease., Methods: This retrospective cohort study utilised nationwide claims data from the Korea Health Insurance Review and Assessment Service for infants under one year of age with confirmed RSV infection in the first year of life from January 2017 to April 2022. The infants were stratified into three subgroups based on their gestational age and health status: unhealthy preterm, healthy preterm, and full-term infants. A descriptive analysis was conducted to estimate healthcare utilization by type of resource and costs related to the treatment of RSV., Results: Out of 93,585 RSV infections identified, 31,206 patients met the inclusion criteria; these included 963 unhealthy preterm, 1,768 healthy preterm and 28,475 full-term infants. In our study, 76.3% of the infants with confirmed RSV infection required intensive care, including hospitalisation and more critical interventions such as intensive care unit (ICU) or mechanical ventilation (MV). The total average cost of RSV management was notably higher for unhealthy preterm infants ($ 6,325; 95% confidence interval (CI): $ 5,484-7,165) than for healthy preterm ($ 1,134; 95% CI: $ 1,006 - 1,261) and full-term infants ($ 606; 95% CI: 583-630). Our findings confirmed a significant epidemiological and economic burden, with infants at greater risk-shorter gestational age and poorer health conditions. Furthermore, we observed a marked increase in the total average cost of RSV management during COVID-19, reflecting the complex interplay between RSV and pandemic-related healthcare dynamics., Conclusion: Our findings provide evidence for the significant economic burden of RSV infection among infants, with considerable disparities based on gestational age and health status subgroups. However, RSV prevention policies should also recognise that healthy preterm or full-term infants who receive intensive care face a significant disease burden., (© 2024. The Author(s).)

Acute lower respiratory tract infections (ALRTIs) are a leading cause of mortality in young children worldwide due to human respiratory syncytial virus (RSV). The aim of this study was to monitor genetic variations in RSV and provide genomic data support for RSV prevention and control. A total of 105 complete RSV genome sequences were determined during 2017-2020. Phylogenetic analysis showed that all of the RSVA sequences were of genotype ON1, and all of the RSVB sequences were of genotype BA9. Notably, a phylogenetic tree based on the whole genome had more branches than a tree based on the G gene. In comparison to the RSV prototype sequences, 71.43% (50/70) of the ON1 sequences had five amino acid substitutions (T113I, V131N, N178G, H258Q, and H266L) that occurred simultaneously, and 68.57% (24/35) of the BA9 genotype sequences had 12 amino acid substitutions, four of which (A131T, T137I, T288I, and T310I) occurred simultaneously. In the F gene, there were 19 amino acid substitutions, which were mainly located in the antigenic sites Ø, II, V, and VII. Other amino acid substitutions were found in the NS1, NS2, P, SH, and L proteins. No significant evidence of recombination was found in any of the sequences. These findings provide important data that will be useful for prevention, control, and vaccine development against RSV., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature.)

Background: Identifying risk factors for respiratory syncytial virus (RSV)-associated severe acute respiratory illness (SARI) will assist with targeting vaccine interventions., Methods: Using surveillance data from South Africa (2012-2018), we compared the characteristics of individuals with RSV-associated influenza-like illness (ILI) (reference group) to those with RSV-associated SARI to describe factors associated with SARI using a multivariable analysis., Results: RSV was detected in 6% (483/7792) of ILI cases and 15% (844/5672) of SARI cases. Factors associated with SARI in children included age < 2 months, compared to age 2-4 years (adjusted odds ratio (aOR) 54.4; 95% confidence interval (CI) 23.5-125.8), malnutrition (aOR 1.9; 95% CI 1.2-3.2), prematurity (aOR 2.4; 95% CI 1.3-4.6) and living with HIV (LWH) (aOR 22.5; 95% CI 2.9-174.3). In individuals ≥ 5 years, factors associated with SARI included age ≥ 65 years compared to age 5-24 years (aOR 10.7; 95% CI 1.1-107.5), symptom duration ≥ 5 days (aOR 2.7; 95% CI 1.1-6.3), underlying illness (aOR 2.7; 95% CI 1.5-26.1) and LWH (aOR 16.8, 95% CI: 4.8-58.2)., Conclusion: Individuals at the extremes of age and those with identified risk factors might benefit most from RSV prevention interventions., Clinical Trial Number: Not applicable, this is not a clinical trial., (© 2024. The Author(s).)

Objective: To investigate the epidemiological characteristics and infections of respiratory syncytial virus (RSV) and influenza viruses in hospitalized elderly patients with respiratory tract infections in Suzhou City, China, and to compare the differences in clinical characteristics and economic burden associated with these two infections., Methods: In this prospective study, pathogenetic testing and clinical data for hospitalized patients aged 60 years and older with respiratory tract infections were collected in five hospitals through stratified cluster sampling from December 2023 to May 2024. Comparative study on epidemic characteristics, clinical features and costs of cases who infected RSV alone and influenza alone were conducted., Results: Among 1,894 cases included, the RSV positivity rate was 5.91% during the 2023-2024 winter-spring season, while the influenza positivity rate was 9.61%. RSV-B was the predominant subtype of RSV, and influenza A (primarily H3N2) was the dominant strain among the influenza-positive cases. Compared with cases infected influenza virus alone, those infected RSV alone had lower occurrence frequency of fever (18.8% vs. 35.7%, P = 0.004), higher occurrence frequency of complications of lower respiratory tract infections (70.8% vs. 54.8%, P = 0.011), higher direct medical costs ($996.2 vs. $841.1, P = 0.017) and total costs ($1019.7 vs. $888.1, P = 0.036). RSV single infection is more common in female cases (P = 0.007) and diabetic cases (P = 0.007) than influenza virus single infection., Conclusions: During the winter and spring months, RSV is the second most common pathogen after influenza virus among older adults hospitalized for respiratory infections in Suzhou, China. Patients infected RSV are more likely to develop complications with lower respiratory tract infections and have higher medical costs than the influenza. RSV infection in the elderly should be emphasized, especially in female patients and diabetic patients., (© 2024. The Author(s).)

Respiratory syncytial virus (RSV) is the commonest cause of lower respiratory tract infection (LRTI) in children, particularly those aged <1 year. In South Africa (SA), increased hospitalisation rates during the RSV season, including access to intensive care facilities, place a huge burden on the healthcare system. Furthermore, RSV-LRTI during early childhood may lead to long-term respiratory sequelae, including recurrent wheezing, asthma, and impairment of lung function. Recently, two new RSV prevention strategies have emerged: nirsevimab, a long-acting monoclonal antibody, and a maternal RSV vaccine. Both strategies have shown high efficacy in reducing RSV-LRTI hospitalisation in infants and are being considered for licensure in SA. Implementation of these prevention strategies, combined with public engagement and collaboration between stakeholders, could significantly reduce RSV-related morbidity and mortality in SA.

This study focuses on the cases(mainly characterized by respiratory symptoms such as cough, runny nose, fever, sore throat, and nasal congestion)of an outbreak of upper respiratory tract infections in a kindergarten in Jingyuan County, Baiyin City, Gansu Province, in May 2023. The epidemiological data were collected, and pharyngeal swab specimens were also obtained from the patients. The specimens of the research participants were subjected to respiratory multi-pathogen testing, and the positive specimens were further analyzed by sequencing the second hypervariable region (HRV2) of the G gene of respiratory syncytial virus (RSV) and constructing a phylogenetic tree. A total of 90 patients were collected, with an incidence rate of 22.84% (90/394), and the highest incidence was observed in the junior class group at 29.55%. Among the 17 pharyngeal swab specimens collected, 16 specimens were identified with the A subtype of respiratory syncytial virus. Sequencing analysis confirmed that it was the A subtype ON1 genotype. Based on the aforementioned testing results, it can be concluded that the current epidemic was primarily caused by infection with the A subtype of respiratory syncytial virus. Following the implementation of intervention measures, the epidemic has been effectively controlled.

Background: Respiratory Syncytial Virus (RSV) is an important pathogen causing acute respiratory illnesses in adults. RSV infection can lead to severe outcomes, including hospitalizations and even death. Despite the increased recognition of the burden in older adults, immediate post-discharge care needs among adults hospitalized with RSV are not well characterized and have not been compared to other serious medical conditions (such as influenza, acute myocardial infarction (MI), and stroke) for which there have been long-standing disease prevention efforts., Objectives: This study aims to describe the immediate post-discharge care needs among adults hospitalized with RSV in the United States and descriptively compare it to those hospitalized with influenza, acute MI, or stroke., Design: Retrospective observational cohort study., Patients: Adults aged ≥ 18 years, hospitalized with a primary diagnosis of RSV, influenza, acute MI, or stroke from January 01, 2016, to December 31, 2019, were identified from the Premier Healthcare Database using the International Classification of Diseases (ICD-10) codes., Main Measures: Immediate post-discharge care was categorized into three different levels of care based on the discharge dispositions. Descriptive analyses were performed., Key Results: In total, 3,629 RSV, 303,577 influenza, 388,682 acute MI, and 416,750 stroke hospitalizations were identified, the majority occurred among patients aged ≥ 65 years. Professional home care needs were the highest for RSV hospitalizations (19.1%), followed by influenza (17.7%), stroke (15.4%), and acute MI (9.8%). Additionally, institutional care needs immediately following discharge were similar for RSV, influenza, and acute MI hospitalizations (14.2%, 15.8%, and 14.1%, respectively)., Conclusions: Immediate post-discharge care needs among adults hospitalized with RSV, especially in older adults, can be considerable and comparable to influenza and acute MI discharges. With recently approved RSV vaccines, efforts to increase vaccination in older adults are needed to prevent RSV and associated healthcare consequences., (© 2024. The Author(s).)

Background: Respiratory syncytial virus (RSV) is the most common cause of hospitalisation in infants aged ≤ 6 months in Western countries. Nearly 1,500 infants under six months of age are hospitalised with RSV annually in Denmark. This nationwide study describes the healthcare resource utilisation and costs related to RSV hospitalisation in this vulnerable age group., Methods: RSV cases were identified in the Danish National Patient Register. Infants were included if they at the age of 0-5 months had a (1) respiratory related hospital admission (duration > 12 h), (2) within 10 days of a positive RSV test, (3) between January 2013 and December 2022. Each case was matched with five individuals never diagnosed with RSV on age, sex, region of residence, birth (pre/full term), number of siblings < 7 years old, and parents' education. An episode of RSV was defined as the seven days prior to hospitalisation to 30 days after initial hospitalisation. Study outcomes included contacts with hospital and primary care, and total healthcare costs defined as the sum cost of hospital care, primary care, and prescription medicine. Cost and contacts attributable to RSV was calculated in a diff-in-diff framework, as the difference between case and reference group., Results: The study population comprised of 8,428 RSV cases and 41,725 reference individuals. Cases generated 1.58 (p < 0.001) attributable inpatient contacts, 0.84 (p < 0.001) outpatient contacts, and 1.19 (p < 0.001) primary care contacts during their RSV episode. An additional 0.6 (p < 0.001) inpatient, 1.08 (p < 0.001) outpatient and 2.42 (p < 0.001) primary care contacts were attributed to RSV in the year following the RSV episode. Total cost of an RSV episode was EUR 2,997 (p < 0.001) with an additional EUR 1,428 (p < 0.001) in the following year., Conclusion: RSV hospitalisations of infants are associated with substantial healthcare utilisation and costs. The same pattern was observed in the year following the RSV episode. If the new RSV prevention options are introduced nationwide, the overall burden of RSV is expected to be substantially reduced in the future., (© 2024. The Author(s).)

Background: Respiratory viruses have clinical and epidemiological importance. With the COVID-19 pandemic, interest has focused on SARS-CoV-2, but as a result, the number of samples available for the differential diagnosis of other respiratory viruses has increased., Study Design: Cross-sectional study., Objective: To describe the epidemiological behavior of respiratory viruses based on a laboratory-based epidemiological surveillance system using data from 2017 to 2023., Methods: Univariate, bivariate and multivariate analyses of data from a laboratory database of respiratory viruses detected by multiplex RT‒qPCR were performed., Results: A total of 4,632 samples with positive results for at least 1 respiratory virus, not including influenza or SARS-CoV-2, were analyzed. The most common virus detected was respiratory syncytial virus in 1,467 (26.3%) samples, followed by rhinovirus in 1,384 (24.8%) samples. Most of the samples were from children under 5 years of age. The age-adjusted odds ratio (OR) of death for patients infected with parainfluenza virus 4 was 4.1 (95% confidence interval [95% CI] 2.0-8.2)., Conclusion: Respiratory syncytial virus and rhinovirus had the highest frequency and proportion of coinfections, whereas parainfluenza virus 4 was associated with an increased risk of death., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Hernández Bautista 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.)

Respiratory disease, attributed to influenza, respiratory syncytial virus (RSV), and SARS-CoV-2, was reported nationally during the 2023/2024 respiratory viral season. The emergence of novel SARS-CoV-2 variants was considered a significant factor contributing to the rise in COVID-19 cases. Data from the Johns Hopkins Hospital System (JHHS) showed that enterovirus/rhinovirus had also been circulating at high rates. Analyzing clinical outcomes of the most prevalent respiratory viruses is crucial for understanding the role of circulating viral genotypes. A retrospective cohort of patients who tested positive for SARS-CoV-2, influenza, RSV, or enterovirus/rhinovirus between 1 June and 31 December 2023 was included in the study. Remnant clinical samples were utilized for targeted viral whole-genome sequencing and genotyping. Patients' metadata and outcomes following infection were studied, stratified by viral variants and genotypes. The increase of SARS-CoV-2 positivity in December was associated with the predominance of JN.1. Admissions for patients under 18 years old were primarily associated with enterovirus/rhinovirus and RSV, while older age groups were mainly linked to SARS-CoV-2 and influenza infections. SARS-CoV-2-related admissions increased with the predominance of the JN.1 variant in December. No significant difference in admissions for influenza subtypes, rhinovirus species, or SARS-CoV-2 variants was observed. RSV A was associated with slightly higher odds of admission compared with RSV B. Our data highlight the importance of systematically analyzing respiratory viral infections to inform public health strategies and clinical management, especially as SARS-CoV-2 becomes endemic. The findings highlight the value of expanded genomic surveillance in elucidating the clinical significance of viral evolution.IMPORTANCEThe analysis of the epidemiology and clinical outcomes of multiple co-circulating respiratory viruses in the early 2023/2024 respiratory virus season highlights the emergence of the SARS-CoV-2 JN.1 variant as well as underscores the importance of enterovirus/rhinovirus in respiratory infections. Understanding these dynamics is essential for refining public health strategies and clinical management, especially as SARS-CoV-2 transitions to an endemic status. This work emphasizes the need for ongoing surveillance, robust diagnostic algorithms, and detailed genomic analyses to anticipate and mitigate the burden of respiratory viral infections, ultimately contributing to more informed decision-making in healthcare settings and better patient outcomes., Competing Interests: H.H.M. reports research collaborations with Hologic, Bio-Rad, and DiaSorin. H.H.M. serves as an advisor for BD Diagnostics and on the advisory board of Seegene. H.H.M. received honoraria from BD Diagnostics and Bio-Rad.

Importance: Bronchiolitis is the most common diagnosis necessitating respiratory support and pediatric intensive care, and respiratory syncytial virus (RSV) is the most common cause of bronchiolitis. In 2023, the monoclonal antibody nirsevimab and the maternal RSVpreF vaccine were implemented to prevent RSV in infants., Objective: To determine the potential association of novel RSV prevention strategies with pediatric intensive care unit (ICU) utilization., Design, Setting, and Participants: This retrospective cross-sectional study examined US pediatric ICU encounters with and without RSV from January 1, 2017, to June 1, 2023. Data were from Oracle Cerner RealWorld Data, a national electronic health record database. All children (aged >1 day and <18 years) admitted to an ICU during the study period were included in the analysis. Statistical analysis was performed from February to May 2024., Main Outcomes and Measures: The primary outcomes were ICU encounters with RSV and ICU encounters with RSV eligible for RSV prevention., Results: There were 119 782 ICU encounters from 53 hospitals; 65 757 encounters (54.9%) were male; median (IQR) age was 4.5 (1.1-12.5) years, median (IQR) ICU length of stay was 1.8 (1.0-3.9) days; 13 702 ICU encounters (11.4%) had RSV, of which 38.6% (5217) were eligible for prevention (4.4% of total ICU encounters). Encounters with RSV accounted for 21.1% (109 334) of ICU days, of which 43.8% (47 888) were eligible for prevention (9.2% of total ICU days). Encounters with RSV were associated with a greater use of positive pressure ventilation (4074 [29.7%] vs 18 821 [17.7%]; P < .001) and vasoactive medications (3057 [22.3%] vs 18 570 [17.5%]; P < .001) compared with those without RSV., Conclusions and Relevance: The findings of this retrospective cross-sectional study of RSV and US pediatric intensive care utilization suggest that if 65% to 85% of eligible children received RSV prevention, an estimated 2.1% to 2.8% reduction in pediatric ICU encounters and an estimated 4.5% to 5.9% reduction in pediatric ICU days could be achieved.

Background: Respiratory viruses are known to represent a high burden in winter, yet the seasonality of many viruses remains poorly understood. Better knowledge of co-circulation and interaction between viruses is critical to prevention and management. We use > 10-year active surveillance in the Valencia Region to assess seasonality and co-circulation., Methods: Over 2010-2021, samples from patients hospitalised for acute respiratory illness were analysed using multiplex real-time PCR to test for 9 viruses: influenza, respiratory syncytial virus (RSV), parainfluenza virus (PIV), rhino/enteroviruses (HRV/ENV), metapneumovirus (MPV), bocavirus, adenovirus, SARS-CoV-2 and non-SARS coronaviruses (HCoV). Winter seasonal patterns of incidence were examined. Instances of co-detection of multiple viruses in a sample were analysed and compared with expected values under a crude model of independent circulation., Results: Most viruses exhibited consistent patterns between years. Specifically, RSV and influenza seasons were clearly defined, peaking in December-February, as did HCoV and SARS-CoV-2. MPV, PIV and HRV/ENV showed less clear seasonality, with circulation outside the observed period. All viruses circulated in January, suggesting any pair had opportunity for co-infection. Multiple viruses were found in 4% of patients, with more common co-detection in children under 5 (9%) than older ages. Influenza co-detection was generally observed infrequently relative to expectation, while RSV co-detections were more common, particularly among young children., Conclusions: We identify characteristic patterns of viruses associated with acute respiratory hospitalisation during winter. Simultaneous circulation permits extensive co-detection of viruses, particularly in young children. However, virus combinations appear to differ in their rates of co-detection, meriting further study., (© 2024 The Author(s). Influenza and Other Respiratory Viruses published by John Wiley & Sons Ltd.)

Objective: To determine the incidence of respiratory viral infections in bone marrow transplant patients., Methods: The prospective, descriptive, cross-sectional study was conducted at a tertiary care hospital in Rawalpindi, Pakistan, from September 2019 to August 2020, and comprised respiratory specimens from recipients of haematopoietic stem cell transplant. The specimens were collected in viral transport medium, and were then taken to the Department of Virology. Multiplex polymerase chain reaction was performed on the specimens to ascertain the incidence and prevalence of respiratory viruses. Data was analysed using SPSS 24., Results: Of the 85 subjects, 53(62.35%) were males and 32(37.65%) were females. The overall median age was 20.0 years (interquartile range: 11.0-32.0 years). Respiratory viral infections were detected in 31(36.4%) specimens. Among them, human rhinovirus was detected in 12(38.7%) cases, respiratory syncytial virus in 5(16.1%), influenza A/H3 in 4(13%), human parainfluenza virus-1 in 3(9.7%), adenovirus in 2(6.4%), human parainfluenza virus-3 in 1(3.2%), human parainfluenza virus-4 in 1(3.2%) and human metapneumovirus in 1(3.2%) case. There were 2(6.4%) cases of co-infection., Conclusions: More than one-third recipients of haematopoietic stem cell transplant were found to have respiratory viral infections, highlighting the importance of employing multiplex respiratory polymerase chain reaction in early diagnosis and treatment of such infections.

BackgroundAfter most COVID-19 pandemic control measures were lifted in 2022, many infectious diseases re-emerged. An increase in invasive group A streptococcal (iGAS) infections among adults and young children was reported by several countries. Viral infections including influenza and varicella, known risk factors for iGAS infection, also increased.AimTo estimate the proportion of GAS skin and soft tissue infections (SSTI) and pneumonia/sepsis in children (≤ 5 years) attributable to varicella, and the proportion of GAS pneumonia/sepsis in children and adults attributable to potentially predisposing respiratory viruses influenza A and B, RSV, hMPV and SARS-CoV-2 in the Netherlands.MethodsWe performed time series regression using weekly data on respiratory viruses, varicella and non-invasive GAS infections and GAS isolates cultured from blood, lower airways, skin, pus and wounds, from January 2010 to March 2023.ResultsIn 2010-19, 50% (95% CI: 36-64) of GAS SSTI in children were attributable to varicella. Between January 2022 and March 2023, 34% (95% CI: 24-43) of GAS SSTI cases were attributable to varicella. Of iGAS pneumonia/sepsis between January 2022 and March 2023, 34% (95% CI: 20-49) and 25% (95% CI: 18-32) was attributable to respiratory virus infections in children and adults, respectively, with the largest contributor (17%) being influenza A.ConclusionsPredisposing viral infections likely contributed to, but cannot fully explain, the observed iGAS increase among children and adults in 2022-23 in the Netherlands. Public health measures to control viral infections, such as vaccination against varicella or influenza, might reduce the iGAS disease burden.