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On June 10, 2005, a tetanus toxoid, reduced diphtheria toxoid and acellular pertussis vaccine (Tdap) formulated for use in adults and adolescents was licensed in the United States for persons aged 11--64 years (ADACEL, manufactured by sanofi pasteur, Toronto, Ontario, Canada). Prelicensure studies demonstrated safety and efficacy, inferred through immunogenicity, against tetanus, diphtheria, and pertussis when Tdap was administered as a single booster dose to adults. To reduce pertussis morbidity among adults and maintain the standard of care for tetanus and diphtheria prevention and to reduce the transmission of pertussis to infants and in health-care settings, the Advisory Committee on Immunization Practices (ACIP) recommends that: 1) adults aged 19-64 years should receive a single dose of Tdap to replace tetanus and diphtheria toxoids vaccine (Td) for booster immunization against tetanus, diphtheria, and pertussis if they received their last dose of Td >10 years earlier and they have not previously received Tdap; 2) intervals shorter than 10 years since the last Td may be used for booster protection against pertussis; 3) adults who have or who anticipate having close contact with an infant aged <12 months (e.g., parents, grandparents aged <65 years, child-care providers, and health-care personnel) should receive a single dose of Tdap to reduce the risk for transmitting pertussis. An interval as short as 2 years from the last Td is suggested; shorter intervals can be used. When possible, women should receive Tdap before becoming pregnant. Women who have not previously received Tdap should receive a dose of Tdap in the immediate postpartum period; 4) health-care personnel who work in hospitals or ambulatory care settings and have direct patient contact should receive a single dose of Tdap as soon as feasible if they have not previously received Tdap. An interval as short as 2 years from the last dose of Td is recommended; shorter intervals may be used. These recommendations for use of Tdap in health-care personnel are supported by the Healthcare Infection Control Practices Advisory Committee (HICPAC). This statement 1) reviews pertussis, tetanus and diphtheria vaccination policy in the United States; 2) describes the clinical features and epidemiology of pertussis among adults; 3) summarizes the immunogenicity, efficacy, and safety data of Tdap; and 4) presents recommendations for the use of Tdap among adults aged 19-64 years. [ABSTRACT FROM AUTHOR]

During spring 2005, two tetanus toxoid, reduced diphtheria toxoid and acellular pertussis vaccine (Tdap) products formulated for use in adolescents (and, for one product, use in adults) were licensed in the United States (BOOSTRIX(R) GlaxoSmithKline Biologicals, Rixensart, Belgium [licensed May 3, 2005, for use in persons aged 10--18 years], and ADACEL[TM], sanofi pasteur, Toronto, Ontario, Canada [licensed June 10, 2005, for use in persons aged 11--64 years]). Prelicensure studies demonstrated safety and efficacy against tetanus, diphtheria, and pertussis when Tdap was administered as a single booster dose to adolescents. To reduce pertussis morbidity in adolescents and maintain the standard of care for tetanus and diphtheria protection, the Advisory Committee on Immunization Practices (ACIP) recommends that: 1) adolescents aged 11--18 years should receive a single dose of Tdap instead of tetanus and diphtheria toxoids vaccine (Td) for booster immunization against tetanus, diphtheria, and pertussis if they have completed the recommended childhood diphtheria and tetanus toxoids and whole cell pertussis vaccine (DTP)/ diphtheria and tetanus toxoids and acellular pertussis vaccine (DTaP) vaccination series (five doses of pediatric DTP/DTaP before the seventh birthday; if the fourth dose was administered on or after the fourth birthday, the fifth dose is not needed) and have not received Td or Tdap. The preferred age for Tdap vaccination is 11--12 years; 2) adolescents aged 11--18 years who received Td, but not Tdap, are encouraged to receive a single dose of Tdap to provide protection against pertussis if they have completed the recommended childhood DTP/DTaP vaccination series. An interval of at least 5 years between Td and Tdap is encouraged to reduce the risk for local and systemic reactions after Tdap vaccination. However, an interval less than 5 years between Td and Tdap can be used; and 3) vaccine providers should administer Tdap and tetravalent meningococcal conjugate vaccine (Menactra(R), sanofi pasteur, Swiftwater, Pennsylvania) to adolescents aged 11--18 years during the same visit if both vaccines are indicated and available. This statement 1) reviews tetanus, diphtheria and pertussis vaccination policy in the United States, with emphasis on adolescents; 2) describes the clinical features and epidemiology of pertussis among adolescents; 3) summarizes the immunogenicity, efficacy, and safety data of the two Tdap vaccines licensed for use among adolescents; and 4) presents recommendations for tetanus, diphtheria, and pertussis vaccination among adolescents aged 11--18 years. [ABSTRACT FROM AUTHOR]

OBJECTIVE: We sought to characterize reports to the Vaccine Adverse Event Reporting System (VAERS) of pregnant women who received tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis vaccine (Tdap). STUDY DESIGN: We searched VAERS for reports of pregnant women who received Tdap from Jan. 1, 2005, through June 30, 2010. We conducted a clinical review of reports and available medical records. RESULTS: We identified 132 reports of Tdap administered to pregnant women; 55 (42%) described no adverse event (AE). No maternal or infant deaths were reported. The most frequent pregnancy-specific AE was spontaneous abortion in 22 (16.7%) reports. Injection site reactions were the most frequent non-pregnancy-specific AE found in 6 (4.5%) reports. One report with a major congenital anomaly (gastroschisis) was identified. CONCLUSION: During a time when Tdap was not routinely recommended in pregnancy, review of reports to VAERS in pregnant women after Tdap did not identify any concerning patterns in maternal, infant, or fetal outcomes. [ABSTRACT FROM AUTHOR]

Advances in technology have led to development of new vaccines for adolescents, but these vaccines will be added to a crowded schedule of recommended adolescent clinical preventive services. We reviewed adolescent clinical preventive health care guidelines and patterns of adolescent clinical preventive service delivery and assessed how new adolescent vaccines might affect health care visits and the delivery of other clinical preventive services. Our analysis suggests that new adolescent immunization recommendations are likely to improve adolescent health, both as a 'needle' and a 'hook.' As a needle, the immunization will enhance an adolescent's health by preventing vaccine-preventable diseases during adolescence and adulthood. It also will likely be a hook to bring adolescents (and their parents) into the clinic for adolescent health care visits, during which other clinical preventive services can be provided. We also speculate that new adolescent immunization recommendations might increase the proportion and quality of other clinical preventive services delivered during health care visits. The factor most likely to diminish the positive influence of immunizations on delivery of other clinical preventive services is the additional visit time required for vaccine counseling and administration. Immunizations may 'crowd out' delivery of other clinical preventive services during visits or reduce the quality of the clinical preventive service delivery. Complementary strategies to mitigate these effects might include prioritizing clinical preventive services with a strong evidence base for effectiveness, spreading clinical preventive services out over several visits, and withholding selected clinical preventive services during a visit if the prevention activity is effectively covered at the community level. Studies are needed to evaluate the effect of new immunizations on adolescent preventive health care visits, delivery of clinical preventive services, and health outcomes. [ABSTRACT FROM AUTHOR]

Adolescents in the United States now have the opportunity to receive new vaccines that prevent invasive meningococcal infections, pertussis (whooping cough), and cervical cancer. Except for their potential to cause serious illness, these infections could not be more different. Their incidence ranges from extremely low to quite high. Early clinical manifestations of infection range from none to life-threatening illness. Two of the vaccines are similar to those already in use, whereas 1 is completely new. In conjunction with the 4 vaccines previously recommended for adolescents (the tetanus and diphtheria booster, hepatitis B, measles-mumps-rubella, and varicella), the 3 new vaccines (meningococcal, human papillomavirus, and the tetanus-diphtheria-pertussis booster [which replaced the tetanus-diphtheria booster]) bring the number recommended for adolescents to 6. In this article, we describe key characteristics of the 3 new vaccines and infections they were designed to prevent. We also briefly discuss other vaccines recommended for all adolescents who have not already received them and new vaccines that are still under development. [ABSTRACT FROM AUTHOR]

This report updates the 2023-24 recommendations of the Advisory Committee on Immunization Practices (ACIP) concerning the use of seasonal influenza vaccines in the United States (MMWR Recomm Rep 2022;72[No. RR-2]:1-24). Routine annual influenza vaccination is recommended for all persons aged ≥6 months who do not have contraindications. Trivalent inactivated influenza vaccines (IIV3s), trivalent recombinant influenza vaccine (RIV3), and trivalent live attenuated influenza vaccine (LAIV3) are expected to be available. All persons should receive an age-appropriate influenza vaccine (i.e., one approved for their age), with the exception that solid organ transplant recipients aged 18 through 64 years who are receiving immunosuppressive medication regimens may receive either high-dose inactivated influenza vaccine (HD-IIV3) or adjuvanted inactivated influenza vaccine (aIIV3) as acceptable options (without a preference over other age-appropriate IIV3s or RIV3). Except for vaccination for adults aged ≥65 years, ACIP makes no preferential recommendation for a specific vaccine when more than one licensed and recommended vaccine is available. ACIP recommends that adults aged ≥65 years preferentially receive any one of the following higher dose or adjuvanted influenza vaccines: trivalent high-dose inactivated influenza vaccine (HD-IIV3), trivalent recombinant influenza vaccine (RIV3), or trivalent adjuvanted inactivated influenza vaccine (aIIV3). If none of these three vaccines is available at an opportunity for vaccine administration, then any other age-appropriate influenza vaccine should be used.Primary updates to this report include the following two topics: the composition of 2024-25 U.S. seasonal influenza vaccines and updated recommendations for vaccination of adult solid organ transplant recipients. First, following a period of no confirmed detections of wild-type influenza B/Yamagata lineage viruses in global surveillance since March 2020, 2024-25 U.S. influenza vaccines will not include an influenza B/Yamagata component. All influenza vaccines available in the United States during the 2024-25 season will be trivalent vaccines containing hemagglutinin derived from 1) an influenza A/Victoria/4897/2022 (H1N1)pdm09-like virus (for egg-based vaccines) or an influenza A/Wisconsin/67/2022 (H1N1)pdm09-like virus (for cell culture-based and recombinant vaccines); 2) an influenza A/Thailand/8/2022 (H3N2)-like virus (for egg-based vaccines) or an influenza A/Massachusetts/18/2022 (H3N2)-like virus (for cell culture-based and recombinant vaccines); and 3) an influenza B/Austria/1359417/2021 (Victoria lineage)-like virus. Second, recommendations for vaccination of adult solid organ transplant recipients have been updated to include HD-IIV3 and aIIV3 as acceptable options for solid organ transplant recipients aged 18 through 64 years who are receiving immunosuppressive medication regimens (without a preference over other age-appropriate IIV3s or RIV3).This report focuses on recommendations for the use of vaccines for the prevention and control of seasonal influenza during the 2024-25 influenza season in the United States. A brief summary of the recommendations and a link to the most recent Background Document containing additional information are available at https://www.cdc.gov/acip-recs/hcp/vaccine-specific/flu.html?CDC&#95;AAref&#95;Val=https://www.cdc.gov/vaccines/hcp/acip-recs/vacc-specific/flu.html. These recommendations apply to U.S.-licensed influenza vaccines. Updates and other information are available from CDC's influenza website (https://www.cdc.gov/flu). Vaccination and health care providers should check this site periodically for additional information., Competing Interests: All authors have completed and submitted the International Committee of Medical Journal Editors form for the disclosure of potential conflicts of interest. No potential conflicts of interest were disclosed. This report includes discussion of the unlabeled use of influenza vaccines in the recommendations for persons with a history of egg allergy and for solid organ transplant recipients aged 18 through 64 years. With regard to persons with a history of egg allergy, history of severe allergic reaction (e.g., anaphylaxis) to the vaccine or any of its components (which include egg for certain vaccines) is a labeled contraindication to receipt of most IIV3s and LAIV3. However, ACIP recommends that all persons aged ≥6 months with egg allergy should receive influenza vaccine. Any influenza vaccine (egg based or nonegg based) that is otherwise appropriate for the recipient’s age and health status can be used. With regard to solid organ transplant recipients aged 18 through 64 years, the high-dose inactivated influenza vaccine (HD-IIV3) and adjuvanted inactivated influenza vaccine (aIIV3) are approved for persons aged ≥65 years. However, ACIP recommends that solid organ transplant recipients aged 18 through 64 years who are receiving immunosuppressive medication regimens may receive either HD-IIV3 or aIIV3 as acceptable options, without a preference over other age-appropriate IIV3s or RIV3.

Respiratory syncytial virus (RSV) is a major cause of respiratory illness and hospitalization in older adults during fall and winter in the United States. The 2023-2024 RSV season was the first during which RSV vaccination was recommended for U.S. adults aged ≥60 years, using shared clinical decision-making. On June 26, 2024, the Advisory Committee on Immunization Practices voted to update this recommendation as follows: a single dose of any Food and Drug Administration-approved RSV vaccine (Arexvy [GSK]; Abrysvo [Pfizer]; or mResvia [Moderna]) is now recommended for all adults aged ≥75 years and for adults aged 60-74 years who are at increased risk for severe RSV disease. Adults who have previously received RSV vaccine should not receive another dose. This report summarizes the evidence considered for these updated recommendations, including postlicensure data on vaccine effectiveness and safety, and provides clinical guidance for the use of RSV vaccines in adults aged ≥60 years. These updated recommendations are intended to maximize RSV vaccination coverage among persons most likely to benefit, by clarifying who is at highest risk and by reducing implementation barriers associated with the previous shared clinical decision-making recommendation. Continued postlicensure monitoring will guide future recommendations., Competing Interests: All authors have completed and submitted the International Committee of Medical Journal Editors form for disclosure of potential conflicts of interest. No potential conflicts of interest were disclosed.

Competing Interests: All authors have completed and submitted the International Committee of Medical Journal Editors form for disclosure of potential conflicts of interest. Phillip G. Blanc reports ownership of Community Health Systems, Inc. stock, sold in 2022. No other potential conflicts of interest were disclosed.

Competing Interests: CONFLICT OF INTEREST DISCLOSURES: The authors have indicated they have no potential conflicts of interest to disclose.

The GSK and Pfizer respiratory syncytial virus (RSV) vaccines are both indicated for adults aged 60 years and older, but only the Pfizer product is approved for use in pregnancy to prevent RSV-associated lower respiratory tract disease in infants aged younger than 6 months. To assess for vaccine administration errors (ie, administration of the GSK RSV vaccine to pregnant persons) VAERS (Vaccine Adverse Event Reporting System), a U.S. passive reporting system, was searched for the time period from August 2023 to January 2024. A total of 113 reports of these administration errors were identified. Most reports (103, 91.2%) did not describe an adverse event. These administration errors are preventable with proper education and training and other preventive measures., (Copyright © 2024 by the American College of Obstetricians and Gynecologists. Published by Wolters Kluwer Health, Inc. All rights reserved.)

The U.S. COVID-19 vaccination program, which commenced in December 2020, has been instrumental in preventing morbidity and mortality from COVID-19 disease. Safety monitoring has been an essential component of the program. The federal government undertook a comprehensive and coordinated approach to implement complementary safety monitoring systems and to communicate findings in a timely and transparent way to healthcare providers, policymakers, and the public. Monitoring involved both well-established and newly developed systems that relied on both spontaneous (passive) and active surveillance methods. Clinical consultation for individual cases of adverse events following vaccination was performed, and monitoring of special populations, such as pregnant persons, was conducted. This report describes the U.S. government's COVID-19 vaccine safety monitoring systems and programs used by the Centers for Disease Control and Prevention, the U.S. Food and Drug Administration, the Department of Defense, the Department of Veterans Affairs, and the Indian Health Service. Using the adverse event of myocarditis following mRNA COVID-19 vaccination as a model, we demonstrate how the multiple, complementary monitoring systems worked to rapidly detect, assess, and verify a vaccine safety signal. In addition, longer-term follow-up was conducted to evaluate the recovery status of myocarditis cases following vaccination. Finally, the process for timely and transparent communication and dissemination of COVID-19 vaccine safety data is described, highlighting the responsiveness and robustness of the U.S. vaccine safety monitoring infrastructure during the national COVID-19 vaccination program., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Katherine Edwards serves as an advisor to Bionet, Dynavax, and IBM, and is on DSMBs Sanofi, X-4 Pharma, Seqirus, Moderna, Pfizer, Merck, Roche, Novavax, and Brighton Collaboration. KM Edwards also reports grants from CDC and NIH. C. Buddy Creech serves as a consults for Pfizer, GSK, Moderna, CommenseBio, and TDCowen. CB Creedch also serves on a DSMB for GSK. Nicola P. Klein reports research support from Pfizer for COVID-19 vaccine clinical trials and from Sanofi Pastuer, Merck, GSK, and Sequirus. unrelated to the work in this manuscript. Matthew Oster serves as the Emory Principal Investigator for a Pfizer-funded NIH study. All other authors have declared that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Published by Elsevier India Pvt Ltd.)

During the COVID-19 pandemic, candidate COVID-19 vaccines were being developed for potential use in the United States on an unprecedented, accelerated schedule. It was anticipated that once available, under U.S. Food and Drug Administration (FDA) Emergency Use Authorization (EUA) or FDA approval, COVID-19 vaccines would be broadly used and potentially administered to millions of individuals in a short period of time. Intensive monitoring in the post-EUA/licensure period would be necessary for timely detection and assessment of potential safety concerns. To address this, the Centers for Disease Control and Prevention (CDC) convened an Advisory Committee on Immunization Practices (ACIP) work group focused solely on COVID-19 vaccine safety, consisting of independent vaccine safety experts and representatives from federal agencies - the ACIP COVID-19 Vaccine Safety Technical Work Group (VaST). This report provides an overview of the organization and activities of VaST, summarizes data reviewed as part of the comprehensive effort to monitor vaccine safety during the COVID-19 pandemic, and highlights selected actions taken by CDC, ACIP, and FDA in response to accumulating post-authorization safety data. VaST convened regular meetings over the course of 29 months, from November 2020 through April 2023; through March 2023 FDA issued EUAs for six COVID-19 vaccines from four different manufacturers and subsequently licensed two of these COVID-19 vaccines. The independent vaccine safety experts collaborated with federal agencies to ensure timely assessment of vaccine safety data during this time. VaST worked closely with the ACIP COVID-19 Vaccines Work Group; that work group used safety data and VaST's assessments for benefit-risk assessments and guidance for COVID-19 vaccination policy. Safety topics reviewed by VaST included those identified in safety monitoring systems and other topics of scientific or public interest. VaST provided guidance to CDC's COVID-19 vaccine safety monitoring efforts, provided a forum for review of data from several U.S. government vaccine safety systems, and assured that a diverse group of scientists and clinicians, external to the federal government, promptly reviewed vaccine safety data. In the event of a future pandemic or other biological public health emergency, the VaST model could be used to strengthen vaccine safety monitoring, enhance public confidence, and increase transparency through incorporation of independent, non-government safety experts into the monitoring process, and through strong collaboration among federal and other partners., 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., (Published by Elsevier Ltd.)

To inform Advisory Committee for Immunization Practices (ACIP) COVID-19 vaccine policy decisions, we developed a benefit-risk assessment framework that directly compared the estimated benefits of COVID-19 vaccination to individuals (e.g., prevention of COVID-19-associated hospitalization) with risks associated with COVID-19 vaccines. This assessment framework originated following the identification of thrombosis with thrombocytopenia syndrome (TTS) after Janssen COVID-19 vaccination in April 2021. We adapted the benefit-risk assessment framework for use in subsequent policy decisions, including the adverse events of myocarditis and Guillain-Barre syndrome (GBS) following mRNA and Janssen COVID-19 vaccination respectively, expansion of COVID-19 vaccine approvals or authorizations to new age groups, and use of booster doses. Over the first year of COVID-19 vaccine administration in the United States (December 2020-December 2021), we used the benefit-risk assessment framework to inform seven different ACIP policy decisions. This framework allowed for rapid and direct comparison of the benefits and potential harms of vaccination, which may be helpful in informing other vaccine policy decisions. The assessments were a useful tool for decision-making but required reliable and granular data to stratify analyses and appropriately focus on populations most at risk for a specific adverse event. Additionally, careful decision-making was needed on parameters for data inputs. Sensitivity analyses were used where data were limited or uncertain; adjustments in the methodology were made over time to ensure the assessments remained relevant and applicable to the policy questions under consideration., 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., (Published by Elsevier Ltd.)

Respiratory syncytial virus (RSV) is the leading cause of hospitalization among U.S. infants. Nirsevimab (Bevfortus, Sanofi and AstraZeneca) is recommended to prevent RSV-associated lower respiratory tract infection (LRTI) in infants. In August 2023, the Food and Drug Administration (FDA) approved RSVpreF vaccine (Abrysvo, Pfizer Inc.) for pregnant persons as a single dose during 32-36 completed gestational weeks (i.e., 32 weeks and zero days' through 36 weeks and 6 days' gestation) to prevent RSV-associated lower respiratory tract disease in infants aged <6 months. Since October 2021, CDC's Advisory Committee on Immunization Practices (ACIP) RSV Vaccines Pediatric/Maternal Work Group has reviewed RSV epidemiology and evidence regarding safety, efficacy, and potential economic impact of pediatric and maternal RSV prevention products, including RSVpreF vaccine. On September 22, 2023, ACIP and CDC recommended RSVpreF vaccine using seasonal administration (i.e., during September through end of January in most of the continental United States) for pregnant persons as a one-time dose at 32-36 weeks' gestation for prevention of RSV-associated LRTI in infants aged <6 months. Either maternal RSVpreF vaccination during pregnancy or nirsevimab administration to the infant is recommended to prevent RSV-associated LRTI among infants, but both are not needed for most infants. All infants should be protected against RSV-associated LRTI through use of one of these products., Competing Interests: All authors and work group members have completed and submitted the International Committee of Medical Journal Editors form for disclosure of potential conflicts of interest. No potential conflicts of interest were disclosed.

Multisystem inflammatory syndrome in children (MIS-C) is a complication of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection; in the United States, reporting of MIS-C after coronavirus disease 2019 (COVID-19) vaccination is required for vaccine safety monitoring. Pfizer-BioNTech COVID-19 vaccine was authorized for children aged 5-11 years on 29 October 2021. Covering a period when approximately 7 million children received vaccine, surveillance for MIS-C ≤ 90 days postvaccination using passive systems identified 58 children with MIS-C and laboratory evidence of past/recent SARS-CoV-2 infection, and 4 without evidence. During a period with extensive SARS-CoV-2 circulation, MIS-C illness in children after COVID-19 vaccination who lacked evidence of SARS-CoV-2 infection was rare (<1 per million vaccinated children)., Competing Interests: Potential conflicts of interest. S. K.'s institution has received funding from National Institutes of Health (NIH) to conduct clinical trials of Moderna and Janssen COVID-19 vaccines, and funding from Pfizer to conduct clinical trials of Pfizer-BioNTech COVID-19 vaccines. M. A. S. reports funding from NIH, CDC, Pfizer, and Merck; and royalties from UpToDate. K. E. reports grant funding from NIH and CDC; consultant to Bionet, GSK, and IBM; and membership of Data Safety and Monitoring Board for Sanofi, X-4 Pharma, Seqirus, Moderna, Pfizer, Merck, and Roche. C. B. C. reports grants from NIH and Merck; royalties from UpToDate; consulting fees from GlaxoSmithKline, Horizon Pharma, Premier Healthcare, Pfizer, Moderna, Cowen Investments, and Vindico; payment for medicolegal testimony from multiple firms (none related to this investigation); a US patent for staphylococcal antibody (number 10 981 979); participation on a data safety monitoring board or advisory board for Astellas; and is President of the Pediatric Infectious Diseases Society. E. P. S. reports grants from the NIH and Pfizer; consulting fees from Sanofi Pasteur; and serves on the Data Safety Monitoring Board for vaccine trials sponsored by the NIH's Division of Microbiology and Infectious Diseases. 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., (Published by Oxford University Press on behalf of Infectious Diseases Society of America 2023.)

Background: Adjuvanted inactivated influenza vaccine (aIIV) and high-dose inactivated influenza vaccine (HD-IIV) are U.S.-licensed for adults aged ≥ 65 years. This study compared serum hemagglutination inhibition (HAI) antibody titers for the A(H3N2) and A(H1N1)pdm09 and B strains after trivalent aIIV3 and trivalent HD-IIV3 in an older adult population., Results: The immunogenicity population included 342 participants who received aIIV3 and 338 participants who received HD-IIV3. The proportion of participants that seroconverted to A(H3N2) vaccine strains after allV3 (112 participants [32.8%]) was inferior to the proportion of participants that seroconverted after HD-IIV3 (130 participants [38.5%]) at day 29 after vaccination (difference, - 5.8%; 95%CI, - 12.9% to 1.4%). There were no significant differences between the vaccine groups in percent seroconversion to A(H1N1)pdm09 or B vaccine strains, in percent seropositivity for any of the strains, or in post-vaccination GMT for the A(H1N1)pdm09 strain. The GMTs for the post-vaccination A(H3N2) and B strains were higher after HD-IIV than after aIIV3., Conclusions: Overall immune responses were similar after aIIV3 and HD-IIV3. For the primary outcome, the aIIV3 seroconversion rate for H3N2 did not meet noninferiority criteria compared with HD-IIV3, but the HD-IIV3 seroconversion rate was not statistically superior to the aIIV3 seroconversion rate., Trial Registration: ClinicalTrials.gov Identifier: NCT03183908., (© 2023. The Author(s).)

Background: The mechanism for anaphylaxis following mRNA COVID-19 vaccination has been widely debated; understanding this serious adverse event is important for future vaccines of similar design. A mechanism proposed is type I hypersensitivity (i.e., IgE-mediated mast cell degranulation) to polyethylene glycol (PEG). Using an assay that, uniquely, had been previously assessed in patients with anaphylaxis to PEG, our objective was to compare anti-PEG IgE in serum from mRNA COVID-19 vaccine anaphylaxis case-patients and persons vaccinated without allergic reactions. Secondarily, we compared anti-PEG IgG and IgM to assess alternative mechanisms., Methods: Selected anaphylaxis case-patients reported to U.S. Vaccine Adverse Event Reporting System December 14, 2020-March 25, 2021 were invited to provide a serum sample. mRNA COVID-19 vaccine study participants with residual serum and no allergic reaction post-vaccination ("controls") were frequency matched to cases 3:1 on vaccine and dose number, sex and 10-year age category. Anti-PEG IgE was measured using a dual cytometric bead assay (DCBA). Anti-PEG IgG and IgM were measured using two different assays: DCBA and a PEGylated-polystyrene bead assay. Laboratorians were blinded to case/control status., Results: All 20 case-patients were women; 17 had anaphylaxis after dose 1, 3 after dose 2. Thirteen (65 %) were hospitalized and 7 (35 %) were intubated. Time from vaccination to serum collection was longer for case-patients vs controls (post-dose 1: median 105 vs 21 days). Among Moderna recipients, anti-PEG IgE was detected in 1 of 10 (10 %) case-patients vs 8 of 30 (27 %) controls (p = 0.40); among Pfizer-BioNTech recipients, it was detected in 0 of 10 case-patients (0 %) vs 1 of 30 (3 %) controls (p >n 0.99). Anti-PEG IgE quantitative signals followed this same pattern. Neither anti-PEG IgG nor IgM was associated with case status with both assay formats., Conclusion: Our results support that anti-PEG IgE is not a predominant mechanism for anaphylaxis post-mRNA COVID-19 vaccination., Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Mary A Staat reports a relationship with Pfizer that includes: funding grants. Mary A Staat reports a relationship with Merck & Co Inc that includes: funding grants. Mary A Staat reports a relationship with UpToDate that includes: consulting or advisory. Donna S. Hummell reports a relationship with Merck & Co Inc that includes: consulting or advisory. Kathryn M. Edwards reports a relationship with Bionet that includes: consulting or advisory. Kathryn M. Edwards reports a relationship with IBM that includes: consulting or advisory. Kathryn M. Edwards reports a relationship with Member Data that includes: consulting or advisory. Kathryn M. Edwards reports a relationship with Sanofi, X-4 Pharma, Seqirus, Moderna, Pfizer, Merck, Roache, Novavax, Brighton Collaboration that includes: consulting or advisory. UpToDate fees for Mary A. Stadt were classified as royalties that are unrelated to this work. Consultative work by Kathryn M. Edwards for X-4 Pharma, Seqirus, Moderna, Pfizer, Merck, Roche, Novavax, Brighton Collaboration was serving on Safety and Monitoring Boards. Consultative work by Donna S. Hummel for Merck was for eDMC monitoring for clinical trial., (Published by Elsevier Ltd.)

Background: Data on medium-term outcomes in indivduals with myocarditis after mRNA COVID-19 vaccination are scarce. We aimed to assess clinical outcomes and quality of life at least 90 days since onset of myocarditis after mRNA COVID-19 vaccination in adolescents and young adults., Methods: In this follow-up surveillance study, we conducted surveys in US individuals aged 12-29 years with myocarditis after mRNA COVID-19 vaccination, for whom a report had been filed to the Vaccine Adverse Event Reporting System between Jan 12 and Nov 5, 2021. A two-component survey was administered, one component to patients (or parents or guardians) and one component to health-care providers, to assess patient outcomes at least 90 days since myocarditis onset. Data collected were recovery status, cardiac testing, and functional status, and EuroQol health-related quality-of-life measures (dichotomised as no problems or any problems), and a weighted quality-of-life measure, ranging from 0 to 1 (full health). The EuroQol results were compared with published results in US populations (aged 18-24 years) from before and early on in the COVID-19 pandemic., Findings: Between Aug 24, 2021, and Jan 12, 2022, we collected data for 519 (62%) of 836 eligible patients who were at least 90 days post-myocarditis onset: 126 patients via patient survey only, 162 patients via health-care provider survey only, and 231 patients via both surveys. Median patient age was 17 years (IQR 15-22); 457 (88%) patients were male and 61 (12%) were female. 320 (81%) of 393 patients with a health-care provider assessment were considered recovered from myocarditis by their health-care provider, although at the last health-care provider follow-up, 104 (26%) of 393 patients were prescribed daily medication related to myocarditis. Of 249 individuals who completed the quality-of-life portion of the patient survey, four (2%) reported problems with self-care, 13 (5%) with mobility, 49 (20%) with performing usual activities, 74 (30%) with pain, and 114 (46%) with depression. Mean weighted quality-of-life measure (0·91 [SD 0·13]) was similar to a pre-pandemic US population value (0·92 [0·13]) and significantly higher than an early pandemic US population value (0·75 [0·28]; p<0·0001). Most patients had improvements in cardiac diagnostic marker and testing data at follow-up, including normal or back-to-baseline troponin concentrations (181 [91%] of 200 patients with available data), echocardiograms (262 [94%] of 279 patients), electrocardiograms (240 [77%] of 311 patients), exercise stress testing (94 [90%] of 104 patients), and ambulatory rhythm monitoring (86 [90%] of 96 patients). An abnormality was noted among 81 (54%) of 151 patients with follow-up cardiac MRI; however, evidence of myocarditis suggested by the presence of both late gadolinium enhancement and oedema on cardiac MRI was uncommon (20 [13%] of 151 patients). At follow-up, most patients were cleared for all physical activity (268 [68%] of 393 patients)., Interpretation: After at least 90 days since onset of myocarditis after mRNA COVID-19 vaccination, most individuals in our cohort were considered recovered by health-care providers, and quality of life measures were comparable to those in pre-pandemic and early pandemic populations of a similar age. These findings might not be generalisable given the small sample size and further follow-up is needed for the subset of patients with atypical test results or not considered recovered., Funding: US Centers for Disease Control and Prevention., Competing Interests: Declaration of interests MEO reports a grant from the US National Institutes of Health (NIH). BC reports a Clinical and Translational Science grant from NIH and participation on the data and safety advisory board for Astellas. EBW reports a grant from Moderna, Pfizer, Sequiris, and NIH, and participation on the data and safety advisory board for Vaxcyte and Iliad Biotechnologies., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Background: The VARIVAX® Pregnancy Registry was established in 1995 to monitor pregnancy outcomes of women who received varicella vaccine (ie, VARIVAX) inadvertently while pregnant., Methods: Health care providers and consumers sent voluntary reports about women who received VARIVAX 3 months before or during pregnancy. Follow-up occurred to evaluate pregnancy outcomes for birth defects. Outcomes from prospectively reported pregnancy exposures (ie, reports received before the outcome of the pregnancy was known) among varicella-zoster virus (VZV)-seronegative women were used to calculate rates and 95% confidence intervals (CIs)., Results: From 17 March 1995 through 16 October 2013, 1601 women were enrolled-966 prospectively-among whom there were 819 live births. Among 164 infants born to women who were VZV seronegative at the time of vaccination, no cases of congenital varicella syndrome (CVS) were identified (rate, 0 per 100, 95% CI, 0.0-2.2) and the birth prevalence of major birth defects was 4.3 per 100 liveborn infants (95% CI 1.7-8.6) with no pattern suggestive of CVS. No defects consistent with CVS were identified in any registry reports., Conclusions: Data collected through the VARIVAX pregnancy registry do not support a relationship between the occurrence of CVS or major birth defects and varicella vaccine exposure during pregnancy, although the small numbers of exposures cannot rule out a low risk. VARIVAX remains contraindicated during pregnancy., Competing Interests: Potential conflicts of interest. E. D. W., A. M. M., and M. McG. are employees of Merck Sharp & Dohme LLC, a subsidiary of Merck & Co, Inc, Rahway, NJ and may own stock or stock options in Merck & Co, Inc, Rahway, NJ. S. A. R. has served on an advisory committee for the Teva Pregnancy Registry; consulted for F. Hoffmann-La Roche AG as a litigation consultant; and receives grant support from the National Institutes of Health, the Centers for Disease Control and Prevention, and Health Services Research Administration. All other 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) 2022. Published by Oxford University Press on behalf of Infectious Diseases Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

THIS REPORT UPDATES THE 2021-22 RECOMMENDATIONS OF THE ADVISORY COMMITTEE ON IMMUNIZATION PRACTICES (ACIP) CONCERNING THE USE OF SEASONAL INFLUENZA VACCINES IN THE UNITED STATES: (MMWR Recomm Rep 2021;70[No. RR-5]:1-24). Routine annual influenza vaccination is recommended for all persons aged ≥6 months who do not have contraindications. For each recipient, a licensed and age-appropriate vaccine should be used. With the exception of vaccination for adults aged ≥65 years, ACIP makes no preferential recommendation for a specific vaccine when more than one licensed, recommended, and age-appropriate vaccine is available. All seasonal influenza vaccines expected to be available in the United States for the 2022-23 season are quadrivalent, containing hemagglutinin (HA) derived from one influenza A(H1N1)pdm09 virus, one influenza A(H3N2) virus, one influenza B/Victoria lineage virus, and one influenza B/Yamagata lineage virus. Inactivated influenza vaccines (IIV4s), recombinant influenza vaccine (RIV4), and live attenuated influenza vaccine (LAIV4) are expected to be available. Trivalent influenza vaccines are no longer available, but data that involve these vaccines are included for reference. INFLUENZA VACCINES MIGHT BE AVAILABLE AS EARLY AS JULY OR AUGUST, BUT FOR MOST PERSONS WHO NEED ONLY 1 DOSE OF INFLUENZA VACCINE FOR THE SEASON, VACCINATION SHOULD IDEALLY BE OFFERED DURING SEPTEMBER OR OCTOBER. HOWEVER, VACCINATION SHOULD CONTINUE AFTER OCTOBER AND THROUGHOUT THE SEASON AS LONG AS INFLUENZA VIRUSES ARE CIRCULATING AND UNEXPIRED VACCINE IS AVAILABLE. FOR MOST ADULTS (PARTICULARLY ADULTS AGED ≥65 YEARS) AND FOR PREGNANT PERSONS IN THE FIRST OR SECOND TRIMESTER, VACCINATION DURING JULY AND AUGUST SHOULD BE AVOIDED UNLESS THERE IS CONCERN THAT VACCINATION LATER IN THE SEASON MIGHT NOT BE POSSIBLE. CERTAIN CHILDREN AGED 6 MONTHS THROUGH 8 YEARS NEED 2 DOSES; THESE CHILDREN SHOULD RECEIVE THE FIRST DOSE AS SOON AS POSSIBLE AFTER VACCINE IS AVAILABLE, INCLUDING DURING JULY AND AUGUST. VACCINATION DURING JULY AND AUGUST CAN BE CONSIDERED FOR CHILDREN OF ANY AGE WHO NEED ONLY 1 DOSE FOR THE SEASON AND FOR PREGNANT PERSONS WHO ARE IN THE THIRD TRIMESTER IF VACCINE IS AVAILABLE DURING THOSE MONTHS: UPDATES DESCRIBED IN THIS REPORT REFLECT DISCUSSIONS DURING PUBLIC MEETINGS OF ACIP THAT WERE HELD ON OCTOBER 20, 2021; JANUARY 12, 2022; FEBRUARY 23, 2022; AND JUNE 22, 2022. PRIMARY UPDATES TO THIS REPORT INCLUDE THE FOLLOWING THREE TOPICS: 1) THE COMPOSITION OF 2022-23 U.S. SEASONAL INFLUENZA VACCINES; 2) UPDATES TO THE DESCRIPTION OF INFLUENZA VACCINES EXPECTED TO BE AVAILABLE FOR THE 2022-23 SEASON, INCLUDING ONE INFLUENZA VACCINE LABELING CHANGE THAT OCCURRED AFTER THE PUBLICATION OF THE 2021-22 ACIP INFLUENZA RECOMMENDATIONS; AND 3) UPDATES TO THE RECOMMENDATIONS CONCERNING VACCINATION OF ADULTS AGED ≥65 YEARS. FIRST, THE COMPOSITION OF 2022-23 U.S. INFLUENZA VACCINES INCLUDES UPDATES TO THE INFLUENZA A(H3N2) AND INFLUENZA B/VICTORIA LINEAGE COMPONENTS. U.S.-LICENSED INFLUENZA VACCINES WILL CONTAIN HA DERIVED FROM AN INFLUENZA A/VICTORIA/2570/2019 (H1N1)PDM09-LIKE VIRUS (FOR EGG-BASED VACCINES) OR AN INFLUENZA A/WISCONSIN/588/2019 (H1N1)PDM09-LIKE VIRUS (FOR CELL CULTURE-BASED OR RECOMBINANT VACCINES); AN INFLUENZA A/DARWIN/9/2021 (H3N2)-LIKE VIRUS (FOR EGG-BASED VACCINES) OR AN INFLUENZA A/DARWIN/6/2021 (H3N2)-LIKE VIRUS (FOR CELL CULTURE-BASED OR RECOMBINANT VACCINES); AN INFLUENZA B/AUSTRIA/1359417/2021 (VICTORIA LINEAGE)-LIKE VIRUS; AND AN INFLUENZA B/PHUKET/3073/2013 (YAMAGATA LINEAGE)-LIKE VIRUS. SECOND, THE APPROVED AGE INDICATION FOR THE CELL CULTURE-BASED INACTIVATED INFLUENZA VACCINE, FLUCELVAX QUADRIVALENT (CCIIV4), WAS CHANGED IN OCTOBER 2021 FROM ≥2 YEARS TO ≥6 MONTHS. THIRD, RECOMMENDATIONS FOR VACCINATION OF ADULTS AGED ≥65 YEARS HAVE BEEN MODIFIED. ACIP RECOMMENDS THAT ADULTS AGED ≥65 YEARS PREFERENTIALLY RECEIVE ANY ONE OF THE FOLLOWING HIGHER DOSE OR ADJUVANTED INFLUENZA VACCINES: QUADRIVALENT HIGH-DOSE INACTIVATED INFLUENZA VACCINE (HD-IIV4), QUADRIVALENT RECOMBINANT INFLUENZA VACCINE (RIV4), OR QUADRIVALENT ADJUVANTED INACTIVATED INFLUENZA VACCINE (AIIV4). IF NONE OF THESE THREE VACCINES IS AVAILABLE AT AN OPPORTUNITY FOR VACCINE ADMINISTRATION, THEN ANY OTHER AGE-APPROPRIATE INFLUENZA VACCINE SHOULD BE USED: THIS REPORT FOCUSES ON RECOMMENDATIONS FOR THE USE OF VACCINES FOR THE PREVENTION AND CONTROL OF SEASONAL INFLUENZA DURING THE 2022-23 INFLUENZA SEASON IN THE UNITED STATES. A BRIEF SUMMARY OF THE RECOMMENDATIONS AND A LINK TO THE MOST RECENT BACKGROUND DOCUMENT CONTAINING ADDITIONAL INFORMATION ARE AVAILABLE AT: https://www.cdc.gov/vaccines/hcp/acip-recs/vacc-specific/flu.html. These recommendations apply to U.S.-licensed influenza vaccines used according to Food and Drug Administration-licensed indications. Updates and other information are available from CDC's influenza website (https://www.cdc.gov/flu). Vaccination and health care providers should check this site periodically for additional information., Competing Interests: All authors have completed and submitted the International Committee of Medical Journal Editors form for the disclosure of potential conflicts of interest. Helen Keipp Talbot reports receiving financial support from CDC. No other potential conflicts of interest were disclosed. This report includes discussion of the unlabeled use of influenza vaccines in the instance of influenza vaccination of persons with a history of egg allergy. A history of severe allergic reaction (e.g., anaphylaxis) to the vaccine or any of its components (which include egg for certain vaccines) is a labeled contraindication to receipt of most IIV4s and LAIV4. However, ACIP recommends that persons with a history of allergic reaction of any severity to egg should receive any licensed, recommended influenza vaccine that is appropriate for their age and health status. Persons with a history of severe allergic reaction to egg who receive egg-based vaccines (i.e., vaccines other than cell culture–based inactivated influenza vaccine [ccIIV4] or recombinant influenza vaccine [RIV4]) should be vaccinated in an inpatient or outpatient medical setting (including, but not necessarily limited to, hospitals, clinics, health departments, and physician offices); vaccine administration in such instances should be supervised by a health care provider who is able to recognize and manage severe allergic reactions. No postvaccination waiting period is recommended specifically for egg-allergic persons. However, ACIP recommends that vaccine providers consider observing patients seated or supine for 15 minutes after administration of any vaccine (regardless of allergy history) to decrease the risk for injury should syncope occur.

Background: Multisystem inflammatory syndrome in adults (MIS-A) was reported in association with the coronavirus disease 2019 (COVID-19) pandemic. MIS-A was included in the list of adverse events to be monitored as part of the emergency use authorizations issued for COVID-19 vaccines., Methods: Reports of MIS-A patients received by the Centers for Disease Control and Prevention (CDC) after COVID-19 vaccines became available were assessed. Data collected on the patients included clinical and demographic characteristics and their vaccine status. The Vaccine Adverse Events Reporting System (VAERS) was also reviewed for possible cases of MIS-A., Results: From 14 December 2020 to 30 April 2021, 20 patients who met the case definition for MIS-A were reported to CDC. Their median age was 35 years (range, 21-66 years), and 13 (65%) were male. Overall, 16 (80%) patients had a preceding COVID-19-like illness a median of 26 days (range 11-78 days) before MIS-A onset. All 20 patients had laboratory evidence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Seven MIS-A patients (35%) received COVID-19 vaccine a median of 10 days (range, 6-45 days) before MIS-A onset; 3 patients received a second dose of COVID-19 vaccine 4, 17, and 22 days before MIS-A onset. Patients with MIS-A predominantly had gastrointestinal and cardiac manifestations and hypotension or shock., Conclusions: Although 7 patients were reported to have received COVID-19 vaccine, all had evidence of prior SARS-CoV-2 infection. Given the widespread use of COVID-19 vaccines, the lack of reporting of MIS-A associated with vaccination alone, without evidence of underlying SARS-CoV-2 infection, is reassuring., (Published by Oxford University Press for the Infectious Diseases Society of America 2021. This work is written by (a) US Government employee(s) and is in the public domain in the US.)

Background: Multisystem inflammatory syndrome in children (MIS-C) is a hyperinflammatory condition associated with antecedent SARS-CoV-2 infection. In the USA, reporting of MIS-C after vaccination is required under COVID-19 vaccine emergency use authorisations. We aimed to investigate reports of individuals aged 12-20 years with MIS-C after COVID-19 vaccination reported to passive surveillance systems or through clinician outreach to the US Centers for Disease Control and Prevention (CDC)., Methods: In this surveillance activity, we investigated potential cases of MIS-C after COVID-19 vaccination reported to CDC's MIS-C national surveillance system, the Vaccine Adverse Event Reporting System (co-administered by CDC and the US Food and Drug Administration), and CDC's Clinical Immunization Safety Assessment Project. A multidisciplinary team adjudicated cases by use of the CDC MIS-C definition. Any positive SARS-CoV-2 serology test satisfied case criteria; although anti-nucleocapsid antibodies indicate previous SARS-CoV-2 infection, anti-spike protein antibodies indicate either past or recent infection or COVID-19 vaccination. We describe the demographic and clinical features of cases, stratified by laboratory evidence of SARS-CoV-2 infection. To calculate the reporting rate of MIS-C, we divided the count of all individuals meeting the MIS-C case definition, and of those without evidence of SARS-CoV-2 infection, by the number of individuals aged 12-20 years in the USA who received one or more COVID-19 vaccine doses up to Aug 31, 2021, obtained from CDC national vaccine surveillance data., Findings: Using surveillance results from Dec 14, 2020, to Aug 31, 2021, we identified 21 individuals with MIS-C after COVID-19 vaccination. Of these 21 individuals, median age was 16 years (range 12-20); 13 (62%) were male and eight (38%) were female. All 21 were hospitalised: 12 (57%) were admitted to an intensive care unit and all were discharged home. 15 (71%) of 21 individuals had laboratory evidence of past or recent SARS-CoV-2 infection, and six (29%) did not. As of Aug 31, 2021, 21 335 331 individuals aged 12-20 years had received one or more doses of a COVID-19 vaccine, making the overall reporting rate for MIS-C after vaccination 1·0 case per million individuals receiving one or more doses in this age group. The reporting rate in only those without evidence of SARS-CoV-2 infection was 0·3 cases per million vaccinated individuals., Interpretation: Here, we describe a small number of individuals with MIS-C who had received one or more doses of a COVID-19 vaccine before illness onset; the contribution of vaccination to these illnesses is unknown. Our findings suggest that MIS-C after COVID-19 vaccination is rare. Continued reporting of potential cases and surveillance for MIS-C illnesses after COVID-19 vaccination is warranted., Funding: US Centers for Disease Control and Prevention., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Background: Thrombosis with thrombocytopenia syndrome (TTS) is a potentially life-threatening condition associated with adenoviral-vectored COVID-19 vaccination. It presents similarly to spontaneous heparin-induced thrombocytopenia. Twelve cases of cerebral venous sinus thrombosis after vaccination with the Ad26.COV2.S COVID-19 vaccine (Janssen/Johnson & Johnson) have previously been described., Objective: To describe surveillance data and reporting rates of all reported TTS cases after COVID-19 vaccination in the United States., Design: Case series., Setting: United States., Patients: Case patients receiving a COVID-19 vaccine from 14 December 2020 through 31 August 2021 with thrombocytopenia and thrombosis (excluding isolated ischemic stroke or myocardial infarction) reported to the Vaccine Adverse Event Reporting System. If thrombosis was only in an extremity vein or pulmonary embolism, a positive enzyme-linked immunosorbent assay for antiplatelet factor 4 antibodies or functional heparin-induced thrombocytopenia platelet test result was required., Measurements: Reporting rates (cases per million vaccine doses) and descriptive epidemiology., Results: A total of 57 TTS cases were confirmed after vaccination with Ad26.COV2.S ( n  = 54) or a messenger RNA (mRNA)-based COVID-19 vaccine ( n  = 3). Reporting rates for TTS were 3.83 per million vaccine doses (Ad26.COV2.S) and 0.00855 per million vaccine doses (mRNA-based COVID-19 vaccines). The median age of patients with TTS after Ad26.COV2.S vaccination was 44.5 years (range, 18 to 70 years), and 69% of patients were women. Of the TTS cases after mRNA-based COVID-19 vaccination, 2 occurred in men older than 50 years and 1 in a woman aged 50 to 59 years. All cases after Ad26.COV2.S vaccination involved hospitalization, including 36 (67%) with intensive care unit admission. Outcomes of hospitalizations after Ad26.COV2.S vaccination included death (15%), discharge to postacute care (17%), and discharge home (68%)., Limitations: Underreporting and incomplete case follow-up., Conclusion: Thrombosis with thrombocytopenia syndrome is a rare but serious adverse event associated with Ad26.COV2.S vaccination. The different demographic characteristics of the 3 cases reported after mRNA-based COVID-19 vaccines and the much lower reporting rate suggest that these cases represent a background rate., Primary Funding Source: Centers for Disease Control and Prevention.

Background and Objectives: Asthma is considered a precaution for use of quadrivalent live attenuated influenza vaccine (LAIV4) in persons aged ≥5 years because of concerns for wheezing events. We evaluated the safety of LAIV4 in children with asthma, comparing the proportion of children with asthma exacerbations after LAIV4 or quadrivalent inactivated influenza vaccine (IIV4)., Methods: We enrolled 151 children with asthma, aged 5 to 17 years, during 2 influenza seasons. Participants were randomly assigned 1:1 to receive IIV4 or LAIV4 and monitored for asthma symptoms, exacerbations, changes in peak expiratory flow rate (PEFR), and changes in the asthma control test for 42 days after vaccination., Results: We included 142 participants in the per-protocol analysis. Within 42 days postvaccination, 18 of 142 (13%) experienced an asthma exacerbation: 8 of 74 (11%) in the LAIV4 group versus 10 of 68 (15%) in the IIV4 group (LAIV4-IIV4 = -0.0390 [90% confidence interval -0.1453 to 0.0674]), meeting the bounds for noninferiority. When adjusted for asthma severity, LAIV4 remained noninferior to IIV4. There were no significant differences in the frequency of asthma symptoms, change in PEFR, or childhood asthma control test/asthma control test scores in the 14 days postvaccination between LAIV4 and IIV4 recipients. Vaccine reactogenicity was similar between groups, although sore throat (P = .051) and myalgia (P <.001) were more common in the IIV4 group., Conclusions: LAIV4 was not associated with increased frequency of asthma exacerbations, an increase in asthma-related symptoms, or a decrease in PEFR compared with IIV4 among children aged 5 to 17 years with asthma., Competing Interests: CONFLICT OF INTEREST DISCLOSURES: The authors report no financial conflicts of interest relevant to this work. Dr. Creech reports receipt of a research grant from Merck Vaccines, personal fees for consultation for Astellas, Horizon Pharma, Altimmune, Janssen, Vir, and Premier Healthcare (unrelated to current work), and royalties from UpToDate (unrelated to current work). Dr. Walter reports serving as principal investigator for Pfizer-funded studies of COVID-19 vaccines, co-investigator for a vaccine study funded by Moderna, and an advisory board member for Vaxcyte (unrelated to current work)., (Copyright © 2022 by the American Academy of Pediatrics.)

Importance: Vaccination against COVID-19 provides clear public health benefits, but vaccination also carries potential risks. The risks and outcomes of myocarditis after COVID-19 vaccination are unclear., Objective: To describe reports of myocarditis and the reporting rates after mRNA-based COVID-19 vaccination in the US., Design, Setting, and Participants: Descriptive study of reports of myocarditis to the Vaccine Adverse Event Reporting System (VAERS) that occurred after mRNA-based COVID-19 vaccine administration between December 2020 and August 2021 in 192 405 448 individuals older than 12 years of age in the US; data were processed by VAERS as of September 30, 2021., Exposures: Vaccination with BNT162b2 (Pfizer-BioNTech) or mRNA-1273 (Moderna)., Main Outcomes and Measures: Reports of myocarditis to VAERS were adjudicated and summarized for all age groups. Crude reporting rates were calculated across age and sex strata. Expected rates of myocarditis by age and sex were calculated using 2017-2019 claims data. For persons younger than 30 years of age, medical record reviews and clinician interviews were conducted to describe clinical presentation, diagnostic test results, treatment, and early outcomes., Results: Among 192 405 448 persons receiving a total of 354 100 845 mRNA-based COVID-19 vaccines during the study period, there were 1991 reports of myocarditis to VAERS and 1626 of these reports met the case definition of myocarditis. Of those with myocarditis, the median age was 21 years (IQR, 16-31 years) and the median time to symptom onset was 2 days (IQR, 1-3 days). Males comprised 82% of the myocarditis cases for whom sex was reported. The crude reporting rates for cases of myocarditis within 7 days after COVID-19 vaccination exceeded the expected rates of myocarditis across multiple age and sex strata. The rates of myocarditis were highest after the second vaccination dose in adolescent males aged 12 to 15 years (70.7 per million doses of the BNT162b2 vaccine), in adolescent males aged 16 to 17 years (105.9 per million doses of the BNT162b2 vaccine), and in young men aged 18 to 24 years (52.4 and 56.3 per million doses of the BNT162b2 vaccine and the mRNA-1273 vaccine, respectively). There were 826 cases of myocarditis among those younger than 30 years of age who had detailed clinical information available; of these cases, 792 of 809 (98%) had elevated troponin levels, 569 of 794 (72%) had abnormal electrocardiogram results, and 223 of 312 (72%) had abnormal cardiac magnetic resonance imaging results. Approximately 96% of persons (784/813) were hospitalized and 87% (577/661) of these had resolution of presenting symptoms by hospital discharge. The most common treatment was nonsteroidal anti-inflammatory drugs (589/676; 87%)., Conclusions and Relevance: Based on passive surveillance reporting in the US, the risk of myocarditis after receiving mRNA-based COVID-19 vaccines was increased across multiple age and sex strata and was highest after the second vaccination dose in adolescent males and young men. This risk should be considered in the context of the benefits of COVID-19 vaccination.

On February 27, 2021, the Food and Drug Administration (FDA) issued an Emergency Use Authorization (EUA) for the adenovirus-vectored COVID-19 vaccine (Janssen Biotech, Inc., a Janssen Pharmaceutical company, Johnson & Johnson), and on February 28, 2021, the Advisory Committee on Immunization Practices (ACIP) issued an interim recommendation for its use as a single-dose primary vaccination in persons aged ≥18 years (1,2). On April 13, 2021, CDC and FDA recommended a pause in the use of Janssen COVID-19 vaccine after reports of thrombosis with thrombocytopenia syndrome (TTS), a rare condition characterized by low platelets and thrombosis, including at unusual sites such as the cerebral venous sinus (cerebral venous sinus thrombosis [CVST]), after receipt of the vaccine.* ACIP rapidly convened two emergency meetings to review reported cases of TTS, and 10 days after the pause commenced, ACIP reaffirmed its interim recommendation for use of the Janssen COVID-19 vaccine in persons aged ≥18 years, but included a warning regarding rare clotting events after vaccination, primarily among women aged 18-49 years (3). In July, after review of an updated benefit-risk assessment accounting for risks of Guillain-Barré syndrome (GBS) and TTS, ACIP concluded that benefits of vaccination with Janssen COVID-19 vaccine outweighed risks. Through ongoing safety surveillance and review of reports from the Vaccine Adverse Event Reporting System (VAERS), additional cases of TTS after receipt of Janssen COVID-19 vaccine, including deaths, were identified. On December 16, 2021, ACIP held an emergency meeting to review updated data on TTS and an updated benefit-risk assessment. At that meeting, ACIP made a recommendation for preferential use of mRNA COVID-19 vaccines over the Janssen COVID-19 vaccine, including both primary and booster doses administered to prevent COVID-19, for all persons aged ≥18 years. The Janssen COVID-19 vaccine may be considered in some situations, including for persons with a contraindication to receipt of mRNA COVID-19 vaccines., Competing Interests: All authors have completed and submitted the International Committee of Medical Journal Editors form for disclosure of potential conflicts of interest. Allison Lale reports personal fees from the Medical Library Association, outside the submitted work. No other potential conflicts of interest were disclosed.

This report updates the 2020-21 recommendations of the Advisory Committee on Immunization Practices (ACIP) regarding the use of seasonal influenza vaccines in the United States (MMWR Recomm Rep 2020;69[No. RR-8]). Routine annual influenza vaccination is recommended for all persons aged ≥6 months who do not have contraindications. For each recipient, a licensed and age-appropriate vaccine should be used. ACIP makes no preferential recommendation for a specific vaccine when more than one licensed, recommended, and age-appropriate vaccine is available. During the 2021-22 influenza season, the following types of vaccines are expected to be available: inactivated influenza vaccines (IIV4s), recombinant influenza vaccine (RIV4), and live attenuated influenza vaccine (LAIV4).The 2021-22 influenza season is expected to coincide with continued circulation of SARS-CoV-2, the virus that causes COVID-19. Influenza vaccination of persons aged ≥6 months to reduce prevalence of illness caused by influenza will reduce symptoms that might be confused with those of COVID-19. Prevention of and reduction in the severity of influenza illness and reduction of outpatient visits, hospitalizations, and intensive care unit admissions through influenza vaccination also could alleviate stress on the U.S. health care system. Guidance for vaccine planning during the pandemic is available at https://www.cdc.gov/vaccines/pandemic-guidance/index.html. Recommendations for the use of COVID-19 vaccines are available at https://www.cdc.gov/vaccines/hcp/acip-recs/vacc-specific/covid-19.html, and additional clinical guidance is available at https://www.cdc.gov/vaccines/covid-19/clinical-considerations/covid-19-vaccines-us.html.Updates described in this report reflect discussions during public meetings of ACIP that were held on October 28, 2020; February 25, 2021; and June 24, 2021. Primary updates to this report include the following six items. First, all seasonal influenza vaccines available in the United States for the 2021-22 season are expected to be quadrivalent. Second, the composition of 2021-22 U.S. influenza vaccines includes updates to the influenza A(H1N1)pdm09 and influenza A(H3N2) components. U.S.-licensed influenza vaccines will contain hemagglutinin derived from an influenza A/Victoria/2570/2019 (H1N1)pdm09-like virus (for egg-based vaccines) or an influenza A/Wisconsin/588/2019 (H1N1)pdm09-like virus (for cell culture-based and recombinant vaccines), an influenza A/Cambodia/e0826360/2020 (H3N2)-like virus, an influenza B/Washington/02/2019 (Victoria lineage)-like virus, and an influenza B/Phuket/3073/2013 (Yamagata lineage)-like virus. Third, the approved age indication for the cell culture-based inactivated influenza vaccine, Flucelvax Quadrivalent (ccIIV4), has been expanded from ages ≥4 years to ages ≥2 years. Fourth, discussion of administration of influenza vaccines with other vaccines includes considerations for coadministration of influenza vaccines and COVID-19 vaccines. Providers should also consult current ACIP COVID-19 vaccine recommendations and CDC guidance concerning coadministration of these vaccines with influenza vaccines. Vaccines that are given at the same time should be administered in separate anatomic sites. Fifth, guidance concerning timing of influenza vaccination now states that vaccination soon after vaccine becomes available can be considered for pregnant women in the third trimester. As previously recommended, children who need 2 doses (children aged 6 months through 8 years who have never received influenza vaccine or who have not previously received a lifetime total of ≥2 doses) should receive their first dose as soon as possible after vaccine becomes available to allow the second dose (which must be administered ≥4 weeks later) to be received by the end of October. For nonpregnant adults, vaccination in July and August should be avoided unless there is concern that later vaccination might not be possible. Sixth, contraindications and precautions to the use of ccIIV4 and RIV4 have been modified, specifically with regard to persons with a history of severe allergic reaction (e.g., anaphylaxis) to an influenza vaccine. A history of a severe allergic reaction to a previous dose of any egg-based IIV, LAIV, or RIV of any valency is a precaution to use of ccIIV4. A history of a severe allergic reaction to a previous dose of any egg-based IIV, ccIIV, or LAIV of any valency is a precaution to use of RIV4. Use of ccIIV4 and RIV4 in such instances should occur in an inpatient or outpatient medical setting under supervision of a provider who can recognize and manage a severe allergic reaction; providers can also consider consulting with an allergist to help identify the vaccine component responsible for the reaction. For ccIIV4, history of a severe allergic reaction (e.g., anaphylaxis) to any ccIIV of any valency or any component of ccIIV4 is a contraindication to future use of ccIIV4. For RIV4, history of a severe allergic reaction (e.g., anaphylaxis) to any RIV of any valency or any component of RIV4 is a contraindication to future use of RIV4. This report focuses on recommendations for the use of vaccines for the prevention and control of seasonal influenza during the 2021-22 influenza season in the United States. A brief summary of the recommendations and a link to the most recent Background Document containing additional information are available at https://www.cdc.gov/vaccines/hcp/acip-recs/vacc-specific/flu.html. These recommendations apply to U.S.-licensed influenza vaccines used according to Food and Drug Administration-licensed indications. Updates and other information are available from CDC's influenza website (https://www.cdc.gov/flu); vaccination and health care providers should check this site periodically for additional information., Competing Interests: All authors have completed and submitted the International Committee of Medical Journal Editors form for the disclosure of potential conflicts of interest. Jill M. Ferdinands reports travel-related support that is unrelated to this work from the Institute for Influenza Epidemiology, which is funded in part by Sanofi Pasteur. Helen Keipp Talbot reports serving as the secretary for the National Foundation for Infectious Diseases, for which she receives no payment. No other potential conflicts of interest were disclosed. This report includes discussion of the unlabeled use of influenza vaccines in the instance of influenza vaccination of persons with a history of egg allergy. A history of severe allergic reaction (e.g., anaphylaxis) to the vaccine or any of its components (which include egg for some vaccines) is a labeled contraindication to receipt of most IIV4s and LAIV4. However, ACIP recommends that persons with a history of allergic reaction of any severity to egg should receive any licensed, recommended influenza vaccine that is appropriate for their age and health status. Persons with a history of severe allergic reaction to egg who receive egg-based vaccines (i.e., vaccines other than cell culture–based inactivated influenza vaccine [ccIIV4] or recombinant influenza vaccine [RIV4]) should be vaccinated in an inpatient or outpatient medical setting (including, but not necessarily limited to, hospitals, clinics, health departments, and physician offices); vaccine administration in such instances should be supervised by a health care provider who is able to recognize and manage severe allergic reactions. No postvaccination waiting period is recommended specifically for egg-allergic persons. However, ACIP recommends that vaccine providers consider observing patients seated or supine for 15 minutes following administration of any vaccine (regardless of allergy history) to decrease the risk for injury should syncope occur.

In December 2020, the Food and Drug Administration (FDA) issued Emergency Use Authorizations (EUAs) for the Pfizer-BioNTech COVID-19 (BNT162b2) vaccine and the Moderna COVID-19 (mRNA-1273) vaccine, † and the Advisory Committee on Immunization Practices (ACIP) issued interim recommendations for their use in persons aged ≥16 years and ≥18 years, respectively. § In May 2021, FDA expanded the EUA for the Pfizer-BioNTech COVID-19 vaccine to include adolescents aged 12-15 years; ACIP recommends that all persons aged ≥12 years receive a COVID-19 vaccine. Both Pfizer-BioNTech and Moderna vaccines are mRNA vaccines encoding the stabilized prefusion spike glycoprotein of SARS-CoV-2, the virus that causes COVID-19. Both mRNA vaccines were authorized and recommended as a 2-dose schedule, with second doses administered 21 days (Pfizer-BioNTech) or 28 days (Moderna) after the first dose. After reports of myocarditis and pericarditis in mRNA vaccine recipients, ¶ which predominantly occurred in young males after the second dose, an ACIP meeting was rapidly convened to review reported cases of myocarditis and pericarditis and discuss the benefits and risks of mRNA COVID-19 vaccination in the United States. Myocarditis is an inflammation of the heart muscle; if it is accompanied by pericarditis, an inflammation of the thin tissue surrounding the heart (the pericardium), it is referred to as myopericarditis. Hereafter, myocarditis is used to refer to myocarditis, pericarditis, or myopericarditis. On June 23, 2021, after reviewing available evidence including that for risks of myocarditis, ACIP determined that the benefits of using mRNA COVID-19 vaccines under the FDA's EUA clearly outweigh the risks in all populations, including adolescents and young adults. The EUA has been modified to include information on myocarditis after receipt of mRNA COVID-19 vaccines. The EUA fact sheets should be provided before vaccination; in addition, CDC has developed patient and provider education materials about the possibility of myocarditis and symptoms of concern, to ensure prompt recognition and management of myocarditis., Competing Interests: All authors have completed and submitted the International Committee of Medical Journal Editors form for disclosure of potential conflicts of interest. No potential conflicts of interest were disclosed.

Importance: Cerebral venous sinus thrombosis (CVST) with thrombocytopenia, a rare and serious condition, has been described in Europe following receipt of the ChAdOx1 nCoV-19 vaccine (Oxford/AstraZeneca), which uses a chimpanzee adenoviral vector. A mechanism similar to autoimmune heparin-induced thrombocytopenia (HIT) has been proposed. In the US, the Ad26.COV2.S COVID-19 vaccine (Janssen/Johnson & Johnson), which uses a human adenoviral vector, received Emergency Use Authorization (EUA) on February 27, 2021. By April 12, 2021, approximately 7 million Ad26.COV2.S vaccine doses had been given in the US, and 6 cases of CVST with thrombocytopenia had been identified among the recipients, resulting in a temporary national pause in vaccination with this product on April 13, 2021., Objective: To describe reports of CVST with thrombocytopenia following Ad26.COV2.S vaccine receipt., Design, Setting, and Participants: Case series of 12 US patients with CVST and thrombocytopenia following use of Ad26.COV2.S vaccine under EUA reported to the Vaccine Adverse Event Reporting System (VAERS) from March 2 to April 21, 2021 (with follow-up reported through April 21, 2021)., Exposures: Receipt of Ad26.COV2.S vaccine., Main Outcomes and Measures: Clinical course, imaging, laboratory tests, and outcomes after CVST diagnosis obtained from VAERS reports, medical record review, and discussion with clinicians., Results: Patients' ages ranged from 18 to younger than 60 years; all were White women, reported from 11 states. Seven patients had at least 1 CVST risk factor, including obesity (n = 6), hypothyroidism (n = 1), and oral contraceptive use (n = 1); none had documented prior heparin exposure. Time from Ad26.COV2.S vaccination to symptom onset ranged from 6 to 15 days. Eleven patients initially presented with headache; 1 patient initially presented with back pain and later developed headache. Of the 12 patients with CVST, 7 also had intracerebral hemorrhage; 8 had non-CVST thromboses. After diagnosis of CVST, 6 patients initially received heparin treatment. Platelet nadir ranged from 9 ×103/µL to 127 ×103/µL. All 11 patients tested for the heparin-platelet factor 4 HIT antibody by enzyme-linked immunosorbent assay (ELISA) screening had positive results. All patients were hospitalized (10 in an intensive care unit [ICU]). As of April 21, 2021, outcomes were death (n = 3), continued ICU care (n = 3), continued non-ICU hospitalization (n = 2), and discharged home (n = 4)., Conclusions and Relevance: The initial 12 US cases of CVST with thrombocytopenia after Ad26.COV2.S vaccination represent serious events. This case series may inform clinical guidance as Ad26.COV2.S vaccination resumes in the US as well as investigations into the potential relationship between Ad26.COV2.S vaccine and CVST with thrombocytopenia.

On February 27, 2021, the Food and Drug Administration (FDA) issued an Emergency Use Authorization (EUA) for the Janssen COVID-19 (Ad.26.COV2.S) vaccine (Janssen Biotech, Inc., a Janssen Pharmaceutical company, Johnson & Johnson; New Brunswick, New Jersey), and on February 28, 2021, the Advisory Committee on Immunization Practices (ACIP) issued interim recommendations for its use in persons aged ≥18 years (1,2). On April 13, 2021, CDC and FDA recommended a pause in the use of the Janssen COVID-19 vaccine after reports of six U.S. cases of cerebral venous sinus thrombosis (CVST) with thrombocytopenia, a rare thromboembolic syndrome, among Janssen COVID-19 vaccine recipients (3). Two emergency ACIP meetings were rapidly convened to review reported cases of thrombosis with thrombocytopenia syndrome (TTS) and to consider updated recommendations for use of the Janssen COVID-19 vaccine in the United States. On April 23, 2021, after a discussion of the benefits and risks of resuming vaccination, ACIP reaffirmed its interim recommendation for use of the Janssen COVID-19 vaccine in all persons aged ≥18 years under the FDA's EUA, which now includes a warning that rare clotting events might occur after vaccination, primarily among women aged 18-49 years. Patient and provider education about the risk for TTS with the Janssen COVID-19 vaccine, especially among women aged <50 years, as well as the availability of alternative COVID-19 vaccines, is required to guide vaccine decision-making and ensure early recognition and clinical management of TTS., Competing Interests: All authors have completed and submitted the International Committee of Medical Journal Editors form for disclosure of potential conflicts of interest. No potential conflicts of interest were disclosed.

Importance: Trivalent adjuvanted inactivated influenza vaccine (aIIV3) and trivalent high-dose inactivated influenza vaccine (HD-IIV3) are US-licensed for adults aged 65 years and older. Data are needed on the comparative safety, reactogenicity, and health-related quality of life (HRQOL) effects of these vaccines., Objective: To compare safety, reactogenicity, and changes in HRQOL scores after aIIV3 vs HD-IIV3., Design, Setting, and Participants: This randomized blinded clinical trial was a multicenter US study conducted during the 2017 to 2018 and 2018 to 2019 influenza seasons. Among 778 community-dwelling adults aged at least 65 years and assessed for eligibility, 13 were ineligible and 8 withdrew before randomization. Statistical analysis was performed from August 2019 to August 2020., Interventions: Intramuscular administration of aIIV3 or HD-IIV3 after age-stratification (65-79 years; ≥80 years) and randomization., Main Outcomes and Measures: Proportions of participants with moderate-to-severe injection-site pain and 14 other solicited reactions during days 1 to 8, using a noninferiority test (5% noninferiority margin), and serious adverse events (SAE) and adverse events of clinical interest (AECI), including new-onset immune-mediated conditions, during days 1 to 43. Changes in HRQOL scores before and after vaccination (days 1, 3) were also compared between study groups., Results: A total of 757 adults were randomized, 378 to receive aIIV3 and 379 to receive HD-IIV3. Of these participants, there were 420 women (55%) and 589 White individuals (78%) with a median (range) age of 72 (65-97) years. The proportion reporting moderate-to-severe injection-site pain, limiting or preventing activity, after aIIV3 (12 participants [3.2%]) (primary outcome) was noninferior compared with HD-IIV3 (22 participants [5.8%]) (difference -2.7%; 95% CI, -5.8 to 0.4). Ten reactions met noninferiority criteria for aIIV3; 4 (moderate-to-severe injection-site tenderness, arthralgia, fatigue, malaise) did not. It was inconclusive whether these 4 reactions occurred in higher proportions of participants after aIIV3. No participant sought medical care for a vaccine reaction. No AECI was observed. Nine participants had at least SAE after aIIV3 (2.4%; 95% CI,1.1% to 4.5%); 3 had at least 1 SAE after HD-IIV3 (0.8%; 95% CI, 0.2% to 2.2%). No SAE was associated with vaccination. Changes in prevaccination and postvaccination HRQOL scores were not clinically meaningful and not different between the groups., Conclusions and Relevance: Overall safety and HRQOL findings were similar after aIIV3 and HD-IIV3, and consistent with prelicensure data. From a safety standpoint, this study's results support using either vaccine to prevent influenza in older adults., Trial Registration: ClinicalTrials.gov Identifier: NCT03183908.

This report updates the 2019-20 recommendations of the Advisory Committee on Immunization Practices (ACIP) regarding the use of seasonal influenza vaccines in the United States (MMWR Recomm Rep 2019;68[No. RR-3]). Routine annual influenza vaccination is recommended for all persons aged ≥6 months who do not have contraindications. For each recipient, a licensed and age-appropriate vaccine should be used. Inactivated influenza vaccines (IIVs), recombinant influenza vaccine (RIV4), and live attenuated influenza vaccine (LAIV4) are expected to be available. Most influenza vaccines available for the 2020-21 season will be quadrivalent, with the exception of MF59-adjuvanted IIV, which is expected to be available in both quadrivalent and trivalent formulations.Updates to the recommendations described in this report reflect discussions during public meetings of ACIP held on October 23, 2019; February 26, 2020; and June 24, 2020. Primary updates to this report include the following two items. First, the composition of 2020-21 U.S. influenza vaccines includes updates to the influenza A(H1N1)pdm09, influenza A(H3N2), and influenza B/Victoria lineage components. Second, recent licensures of two new influenza vaccines, Fluzone High-Dose Quadrivalent and Fluad Quadrivalent, are discussed. Both new vaccines are licensed for persons aged ≥65 years. Additional changes include updated discussion of contraindications and precautions to influenza vaccination and the accompanying Table, updated discussion concerning use of LAIV4 in the setting of influenza antiviral medication use, and updated recommendations concerning vaccination of persons with egg allergy who receive either cell culture-based IIV4 (ccIIV4) or RIV4.The 2020-21 influenza season will coincide with the continued or recurrent circulation of SARS-CoV-2 (the novel coronavirus associated with coronavirus disease 2019 [COVID-19]). Influenza vaccination of persons aged ≥6 months to reduce prevalence of illness caused by influenza will reduce symptoms that might be confused with those of COVID-19. Prevention of and reduction in the severity of influenza illness and reduction of outpatient illnesses, hospitalizations, and intensive care unit admissions through influenza vaccination also could alleviate stress on the U.S. health care system. Guidance for vaccine planning during the pandemic is available at https://www.cdc.gov/vaccines/pandemic-guidance/index.html.This report focuses on recommendations for the use of vaccines for the prevention and control of seasonal influenza during the 2020-21 season in the United States. A brief summary of the recommendations and a link to the most recent Background Document containing additional information are available at https://www.cdc.gov/vaccines/hcp/acip-recs/vacc-specific/flu.html. These recommendations apply to U.S.-licensed influenza vaccines used within Food and Drug Administration (FDA)-licensed indications. Updates and other information are available from CDC's influenza website (https://www.cdc.gov/flu). Vaccination and health care providers should check this site periodically for additional information., Competing Interests: All authors have completed and submitted the International Committee of Medical Journal Editors form for the disclosure of potential conflicts of interest. No potential conflicts of interest were disclosed.

Background: Administering inactivated influenza vaccine (IIV), 13-valent pneumococcal conjugate vaccine (PCV13), and diphtheria-tetanus-acellular pertussis (DTaP) vaccine together has been associated with increased risk for febrile seizure after vaccination. We assessed the effect of administering IIV at a separate visit from PCV13 and DTaP on postvaccination fever., Methods: In 2017-2018, children aged 12 to 16 months were randomly assigned to receive study vaccines simultaneously or sequentially. They had 2 study visits 2 weeks apart; nonstudy vaccines were permitted at visit 1. The simultaneous group received PCV13, DTaP, and quadrivalent IIV (IIV4) at visit 1 and no vaccines at visit 2. The sequential group received PCV13 and DTaP at visit 1 and IIV4 at visit 2. Participants were monitored for fever (≥38°C) and antipyretic use during the 8 days after visits., Results: There were 110 children randomly assigned to the simultaneous group and 111 children to the sequential group; 90% received ≥1 nonstudy vaccine at visit 1. Similar proportions of children experienced fever on days 1 to 2 after visits 1 and 2 combined (simultaneous [8.1%] versus sequential [9.3%]; adjusted relative risk = 0.87 [95% confidence interval 0.36-2.10]). During days 1 to 2 after visit 1, more children in the simultaneous group received antipyretics (37.4% vs 22.4%; P = .020)., Conclusions: In our study, delaying IIV4 administration by 2 weeks in children receiving DTaP and PCV13 did not reduce fever occurrence after vaccination. Reevaluating this strategy to prevent fever using an IIV4 with a different composition in a future influenza season may be considered., Competing Interests: POTENTIAL CONFLICT OF INTEREST: Dr Klein reports potential conflicts due to support received from GlaxoSmithKline, Sanofi Pasteur, Pfizer, Merck, Protein Science (now Sanofi Pasteur), Dynavax, and MedImmune; the other authors have indicated they have no potential conflicts of interest to disclose., (Copyright © 2020 by the American Academy of Pediatrics.)

This report updates the 2018-19 recommendations of the Advisory Committee on Immunization Practices (ACIP) regarding the use of seasonal influenza vaccines in the United States (MMWR Recomm Rep 2018;67[No. RR-3]). Routine annual influenza vaccination is recommended for all persons aged ≥6 months who do not have contraindications. A licensed, recommended, and age-appropriate vaccine should be used. Inactivated influenza vaccines (IIVs), recombinant influenza vaccine (RIV), and live attenuated influenza vaccine (LAIV) are expected to be available for the 2019-20 season. Standard-dose, unadjuvanted, inactivated influenza vaccines will be available in quadrivalent formulations (IIV4s). High-dose (HD-IIV3) and adjuvanted (aIIV3) inactivated influenza vaccines will be available in trivalent formulations. Recombinant (RIV4) and live attenuated influenza vaccine (LAIV4) will be available in quadrivalent formulations.Updates to the recommendations described in this report reflect discussions during public meetings of ACIP held on October 25, 2018; February 27, 2019; and June 27, 2019. Primary updates in this report include the following two items. First, 2019-20 U.S. trivalent influenza vaccines will contain hemagglutinin (HA) derived from an A/Brisbane/02/2018 (H1N1)pdm09-like virus, an A/Kansas/14/2017 (H3N2)-like virus, and a B/Colorado/06/2017-like virus (Victoria lineage). Quadrivalent influenza vaccines will contain HA derived from these three viruses, and a B/Phuket/3073/2013-like virus (Yamagata lineage). Second, recent labeling changes for two IIV4s, Afluria Quadrivalent and Fluzone Quadrivalent, are discussed. The age indication for Afluria Quadrivalent has been expanded from ≥5 years to ≥6 months. The dose volume for Afluria Quadrivalent is 0.25 mL for children aged 6 through 35 months and 0.5 mL for all persons aged ≥36 months (≥3 years). The dose volume for Fluzone Quadrivalent for children aged 6 through 35 months, which was previously 0.25 mL, is now either 0.25 mL or 0.5 mL. The dose volume for Fluzone Quadrivalent is 0.5 mL for all persons aged ≥36 months (≥3 years).This report focuses on the recommendations for use of vaccines for the prevention and control of influenza during the 2019-20 season in the United States. A brief summary of these recommendations and a Background Document containing additional information are available at https://www.cdc.gov/vaccines/hcp/acip-recs/vacc-specific/flu.html. These recommendations apply to U.S.-licensed influenza vaccines used within Food and Drug Administration-licensed indications. Updates and other information are available from CDC's influenza website (https://www.cdc.gov/flu). Vaccination and health care providers should check this site periodically for additional information., Competing Interests: The authors each report that they have nothing to disclose. This report includes discussion of the unlabeled use of influenza vaccines in the instance of influenza vaccination of persons with a history of egg allergy. A history of severe allergic reaction to the vaccine or any of its components (which include egg for some vaccines) is a labeled contraindication to receipt of most IIVs and LAIV4. However, ACIP and CDC recommended that persons with a history of allergic reaction of any severity to egg should receive any licensed, recommended influenza vaccine that is appropriate for their age and health status. Persons with a history of severe allergic reaction to egg should be vaccinated in an inpatient or outpatient medical setting (including, but not necessarily limited to, hospitals, clinics, health departments, and physician offices); vaccine administration should be supervised by a health care provider who is able to recognize and manage severe allergic reactions. No postvaccination waiting period is recommended specifically for egg-allergic persons. However, ACIP recommends that vaccine providers consider observing patients (seated or supine) for 15 minutes following administration of any vaccine to decrease the risk for injury should syncope occur.

Objective: Tetanus toxoid, reduced diphtheria toxoid, and acellular pertusiss (Tdap) vaccine is recommended during each pregnancy, regardless of prior receipt. Data on reactogenicity and immunogenicity, particularly after repeated Tdap, are limited. We compared local injection-site and systemic reactions and serologic response following Tdap in (1) pregnant and nonpregnant women and (2) pregnant women by self-reported prior Tdap receipt., Study Design: Pregnant women (gestational age 20-34 weeks) and nonpregnant women receiving Tdap were enrolled in this observational study. Injection-site and systemic reactions were assessed for one week post-vaccination. Pertussis toxin, filamentous hemagglutinin, pertactin, fimbriae, tetanus and diphtheria specific IgG antibody titers were determined by standardized enzyme-linked immunosorbent assay at baseline and 28 days post-vaccination. Reactogenicity and serologic responses were compared by pregnancy status, and within pregnant women by self-reported prior Tdap receipt., Results: 374 pregnant and 225 nonpregnant women were vaccinated. Severe local or systemic reactions or "any" fever were uncommon (≤3% for both groups). Moderate/severe injection-site pain was significantly higher in pregnant (17.9%) versus nonpregnant (11.1%) women, but did not prompt a healthcare visit. Proportions of other moderate/severe or any severe reactions were not significantly higher in pregnant compared to nonpregnant women. Moderate/severe (including pain) and severe reactions were not significantly higher in pregnant women receiving repeat versus first-time Tdap. Antibody titers increased from baseline to post-vaccination for all vaccine antigens in pregnant and nonpregnant women; post-vaccination titers against pertussis toxin and filamentous hemagglutinin were significantly higher in nonpregnant versus pregnant women (p < 0.01)., Conclusion: Tdap was well-tolerated in pregnant and nonpregnant women. Pregnant women were more likely to report moderate/severe pain at the Tdap injection-site compared with nonpregnant women, but did not necessitate medical visits. Prior Tdap receipt did not increase occurrence of moderate/severe local or systemic reactions in pregnant women. Serologic responses to all vaccine antigens were robust. Clinical Trial Registration@ClinicalTrials.gov. NCT02209623. https://clinicaltrials.gov/ct2/show/NCT02209623., (Copyright © 2018. Published by Elsevier Ltd.)

This report updates the 2017-18 recommendations of the Advisory Committee on Immunization Practices (ACIP) regarding the use of seasonal influenza vaccines in the United States (MMWR Recomm Rep 2017;66[No. RR-2]). Routine annual influenza vaccination is recommended for all persons aged ≥6 months who do not have contraindications. A licensed, recommended, and age-appropriate vaccine should be used. Inactivated influenza vaccines (IIVs), recombinant influenza vaccine (RIV), and live attenuated influenza vaccine (LAIV) are expected to be available for the 2018-19 season. Standard-dose, unadjuvanted, inactivated influenza vaccines will be available in quadrivalent (IIV4) and trivalent (IIV3) formulations. Recombinant influenza vaccine (RIV4) and live attenuated influenza vaccine (LAIV4) will be available in quadrivalent formulations. High-dose inactivated influenza vaccine (HD-IIV3) and adjuvanted inactivated influenza vaccine (aIIV3) will be available in trivalent formulations.Updates to the recommendations described in this report reflect discussions during public meetings of ACIP held on October 25, 2017; February 21, 2018; and June 20, 2018. New and updated information in this report includes the following four items. First, vaccine viruses included in the 2018-19 U.S. trivalent influenza vaccines will be an A/Michigan/45/2015 (H1N1)pdm09-like virus, an A/Singapore/INFIMH-16-0019/2016 (H3N2)-like virus, and a B/Colorado/06/2017-like virus (Victoria lineage). Quadrivalent influenza vaccines will contain these three viruses and an additional influenza B vaccine virus, a B/Phuket/3073/2013-like virus (Yamagata lineage). Second, recommendations for the use of LAIV4 (FluMist Quadrivalent) have been updated. Following two seasons (2016-17 and 2017-18) during which ACIP recommended that LAIV4 not be used, for the 2018-19 season, vaccination providers may choose to administer any licensed, age-appropriate influenza vaccine (IIV, RIV4, or LAIV4). LAIV4 is an option for those for whom it is appropriate. Third, persons with a history of egg allergy of any severity may receive any licensed, recommended, and age-appropriate influenza vaccine (IIV, RIV4, or LAIV4). Additional recommendations concerning vaccination of egg-allergic persons are discussed. Finally, information on recent licensures and labeling changes is discussed, including expansion of the age indication for Afluria Quadrivalent (IIV4) from ≥18 years to ≥5 years and expansion of the age indication for Fluarix Quadrivalent (IIV4), previously licensed for ≥3 years, to ≥6 months.This report focuses on the recommendations for use of vaccines for the prevention and control of influenza during the 2018-19 season in the United States. A Background Document containing further information and a brief summary of these recommendations are available at https://www.cdc.gov/vaccines/hcp/acip-recs/vacc-specific/flu.html.These recommendations apply to U.S.-licensed influenza vaccines used within Food and Drug Administration-licensed indications. Updates and other information are available at CDC's influenza website (https://www.cdc.gov/flu). Vaccination and health care providers should check CDC's influenza website periodically for additional information., Competing Interests: Recommendations for routine use of vaccines in children, adolescents, and adults are developed by the Advisory Committee on Immunization Practices (ACIP). ACIP is chartered as a federal advisory committee to provide expert external advice and guidance to the Director of CDC on use of vaccines and related agents for the control of vaccine-preventable diseases in the civilian population of the United States. Recommendations for routine use of vaccines in children and adolescents are harmonized to the greatest extent possible with recommendations made by the American Academy of Pediatrics (AAP), the American Academy of Family Physicians (AAFP), and the American College of Obstetricians and Gynecologists (ACOG). Recommendations for routine use of vaccines in adults are harmonized with recommendations of AAFP, ACOG, and the American College of Physicians (ACP). ACIP recommendations approved by the CDC Director become agency guidelines on the date published in the Morbidity and Mortality Weekly Report (MMWR). Additional information is available at https://www.cdc.gov/vaccines/acip. Emmanuel B. Walter reports grants from Novavax and Merck & Co, outside the submitted work. Other content experts and CDC planners wish to disclose they have no financial interests or other relationships with the manufacturers of commercial products, suppliers of commercial services, or commercial supporters. This report includes discussion of the unlabeled use of influenza vaccines in the instance of vaccination of persons with a history of egg allergy. A history of severe allergic reaction to influenza vaccine or any of its components (including egg) is a labeled contraindication to receipt of most IIVs and LAIV. However, ACIP and CDC recommend that persons with egg allergy of any severity should receive any licensed, recommended, and age-appropriate influenza vaccine that is otherwise appropriate for their health status. Persons with a history of severe allergic reaction to egg should be vaccinated in an inpatient or outpatient medical setting (including, but not necessarily limited to, hospitals, clinics, health departments, and physician offices). Vaccine administration should be supervised by a health care provider who is able to recognize and manage severe allergic conditions. No postvaccination observation period is recommended specifically for egg-allergic persons. However, ACIP recommends that vaccine providers consider observing patients (seated or supine) for 15 minutes following administration of any vaccine to decrease the risk for injury should syncope occur.

A 2-year-old boy with influenza B infection and rapidly worsening targetoid skin lesions with mucosal involvement was diagnosed with Stevens-Johnson syndrome (SJS) and treated with oseltamivir and intravenous immunoglobulin, with resolution of illness. Subsequent quadrivalent inactivated influenza vaccine was well tolerated. This case highlights the rarity of SJS in the setting of influenza B infection and addresses the safety of administering subsequent influenza vaccines to such individuals., (© 2017 Wiley Periodicals, Inc.)

Background: Using text messaging for vaccine safety monitoring, particularly for non-medically attended events, would be valuable for pandemic influenza and emergency vaccination program preparedness. We assessed the feasibility and acceptability of text messaging to evaluate fever and wheezing post-influenza vaccination in a prospective, observational, multi-site pediatric study., Methods: Children aged 2-11 years old, with an emphasis on children with asthma, were recruited during the 2014-2015 influenza season from three community-based clinics in New York City, and during the 2014-2015 and 2015-2016 seasons from a private practice in Fall River, Massachusetts. Parents of enrolled children receiving quadrivalent live attenuated (LAIV4) or inactivated influenza vaccine (IIV4) replied to text messages assessing respiratory symptoms (day 3 and 7, then weekly through day 42), and temperature on the night of vaccination and the next seven nights (day 0-7). Missing data were collected via diary (day 0-7 only) and phone. Phone confirmation was obtained for both presence and absence of respiratory symptoms. Reporting rates, fever (T≥100.4 °F) frequency, proportion of wheezing and/or chest tightness reports captured via text message versus all sources (text, phone, diary, electronic health record) and parental satisfaction were assessed., Results: Across both seasons, 266 children were analyzed; 49.2% with asthma. Parental text message response rates were high (>70%) across sites. Overall, fever frequency was low (day 0-2: 4.1% [95% confidence interval (CI) 2.3-7.4%]; d3-7: 6.7% [95% CI 4.1-10.8%]). A third (39.2%) of parents reported a respiratory problem in their child, primarily cough. Most (88.2%) of the 52 wheezing and/or chest tightness reports were by text message. Most (88.1%) participants preferred text messaging over paper reporting., Conclusions: Text messaging can provide information about pediatric post-vaccination fever and wheezing and was viewed positively by parents. It could be a helpful tool for rapid vaccine safety monitoring during a pandemic or other emergency vaccination program., Trial Registration: clinicaltrials.gov Identifier: NCT02295007., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Background: Antipyretics reduce fever following childhood vaccinations; after inactivated influenza vaccine (IIV) they might ameliorate fever and thereby decrease febrile seizure risk, but also possibly blunt the immune response. We assessed the effect of antipyretics on immune responses and fever following IIV in children ages 6 through 47 months., Methods: Over the course of three seasons, one hundred forty-two children, receiving either a single or the first of 2 recommended doses of IIV, were randomized to receive either oral acetaminophen suspension (n = 59) or placebo (n = 59) (double-blinded) or ibuprofen (n = 24) (open-label) immediately following IIV and every 4-8 h thereafter for 24 h. Blood samples were obtained at enrollment and 4 weeks following the last recommended IIV dose. Responses to IIV were assessed by hemagglutination inhibition assay (HAI). Seroprotection was defined as an HAI titer ≥1:40 and seroconversion as a titer ≥1:40 if baseline titer <1:10 or four-fold rise if baseline titer ≥1:10. Participants were monitored for fever and other solicited symptoms on the day of and day following IIV., Results: Significant differences in seroconversion and post-vaccination seroprotection were not observed between children included in the different antipyretic groups and the placebo group for the vaccine antigens included in IIV over the course of the studies. Frequencies of solicited symptoms, including fever, were similar between treatment groups and the placebo group., Conclusions: Significant blunting of the immune response was not observed when antipyretics were administered to young children receiving IIV. Studies with larger sample sizes are needed to definitively establish the effect of antipyretics on IIV immunogenicity., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Background and Objectives: Postvaccination syncope can cause injury. Drinking water prephlebotomy increases peripheral vascular tone, decreasing risk of blood-donation presyncope and syncope. This study evaluated whether drinking water prevaccination reduces postvaccination presyncope, a potential syncope precursor., Methods: We conducted a randomized trial of subjects aged 11 to 21 years receiving ≥1 intramuscular vaccine in primary care clinics. Intervention subjects were encouraged to drink 500 mL of water, with vaccination recommended 10 to 60 minutes later. Control subjects received usual care. Presyncope symptoms were assessed with a 12-item survey during the 20-minutes postvaccination. Symptoms were classified with a primary cutoff sensitive for presyncope, and a secondary, more restrictive cutoff requiring greater symptoms. Results were adjusted for clustering by recruitment center., Results: There were 906 subjects randomly assigned to the control group and 901 subjects randomly assigned to the intervention group. None had syncope. Presyncope occurred in 36.2% of subjects by using the primary definition, and in 8.0% of subjects by using the restrictive definition. There were no significant differences in presyncope by intervention group for the primary (1-sided test, P = .24) or restrictive outcome (1-sided test, P = .17). Among intervention subjects vaccinated within 10 to 60 minutes after drinking all 500 mL of water ( n = 519), no reduction in presyncope was observed for the primary or restrictive outcome (1-sided tests, P = .13, P = .17). In multivariable regression analysis, presyncope was associated with younger age, history of passing out or nearly passing out after a shot or blood draw, prevaccination anxiety, receiving >1 injected vaccine, and greater postvaccination pain., Conclusions: Drinking water before vaccination did not prevent postvaccination presyncope. Predictors of postvaccination presyncope suggest opportunities for presyncope and syncope prevention interventions., Competing Interests: POTENTIAL CONFLICT OF INTEREST: The authors have indicated they have no potential conflicts of interest to disclose., (Copyright © 2017 by the American Academy of Pediatrics.)

Background: Some studies have found a higher frequency of fever with trivalent live attenuated influenza vaccine (LAIV) than with inactivated influenza vaccine (IIV), but quadrivalent LAIV has not been assessed. Understanding fever is important for safety reviews and for parents and providers. In addition, there have been only a limited number of studies in which text messaging was used for vaccine adverse-event (AE) surveillance., Methods: We conducted a prospective observational study in 3 community clinics in New York City to assess post-influenza vaccination fever in 24- to 59-month-olds during the 2013-2014 season. Enrolled families of children who received quadrivalent LAIV (LAIV4) or IIV (trivalent IIV3 or quadrivalent IIV4) replied to text messages that assessed their temperature on vaccination night and the next 10 nights (days 0 to 10); missing data were collected via telephone and a diary. We compared frequencies of fever (temperature ≥ 100.4°F) according to vaccine group on days 0 to 2 and 3 to 10 by using χ2 and multivariate log-binomial regression adjusted for age, previous influenza vaccination, and vaccine coadministration. We also assessed outcomes using all sources versus only text messages., Results: Most (84.1% [n = 540]) eligible parents enrolled. Fever frequencies on days 0 to 2 did not differ between LAIV4 and any IIV (3.8% vs 5.7%, respectively; adjusted relative risk [aRR] [95% confidence interval], 0.60 [0.25-1.46]), between LAIV4 and IIV4 (4.2% vs 7.1%, respectively; aRR, 0.58 [0.19-1.72]), or between IIV4 and IIV3 (7.1% vs 6.0%, respectively; aRR, 1.02 [0.30-3.46]). The findings were similar when all data sources versus text-message data alone were used. There were no significant differences on days 3 to 10., Conclusions: Postvaccination fever frequencies were low overall and did not differ according to influenza vaccine type during the 2013-2014 influenza season. The similarity of results when data were limited to text messages lends support to its use for surveillance of vaccine adverse events., (© The Author 2016. Published by Oxford University Press on behalf of the Pediatric Infectious Diseases Society. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.)

Introduction: The feasibility and accuracy of text messaging to monitor events after influenza vaccination throughout pregnancy and the neonatal period has not been studied, but may be important for seasonal and pandemic influenza vaccines and future maternal vaccines., Methods: This prospective observational study was conducted during 2013-2014 and analyzed in 2015-2016. Enrolled pregnant women receiving inactivated influenza vaccination at a gestational age <20 weeks were sent text messages intermittently through participant-reported pregnancy end to request fever, health events, and neonatal outcomes. Text message response rates, Day 0-2 fever (≥100.4°F), health events, and birth/neonatal outcomes were assessed., Results: Most (80.2%, n=166) eligible women enrolled. Median gestational age was 8.9 (SD=3.9) weeks at vaccination. Response rates remained high (80.0%-95.2%). Only one Day 0-2 fever was reported. Women reported via text both pregnancy- and non-pregnancy-specific health events, not all associated with medical visits. Most pregnancy-specific events in the electronic medical record (EMR) were reported via text message. Of all enrollees, 84.9% completed the study (131 reported live birth, ten reported pregnancy loss). Two losses reported via text were not medically attended; there was one additional EMR-identified loss. Gestational age and weight at birth were similar between text message-reported and EMR-abstracted data and 95% CIs were overlapping for proportions of prematurity, low birth weight, small for gestational age, and major birth defects, as identified by text message-reported versus EMR-abstracted plus text message-reported versus EMR-abstracted data only., Conclusions: This study demonstrated the feasibility of text messaging for influenza vaccine safety surveillance sustained throughout pregnancy. In these women receiving inactivated influenza vaccination during pregnancy, post-vaccination fever was infrequent and a typical pattern of maternal and neonatal health outcomes was observed., (Copyright © 2017 American Journal of Preventive Medicine. All rights reserved.)

This report updates the 2016-17 recommendations of the Advisory Committee on Immunization Practices (ACIP) regarding the use of seasonal influenza vaccines (MMWR Recomm Rep 2016;65[No. RR-5]). Routine annual influenza vaccination is recommended for all persons aged ≥6 months who do not have contraindications. A licensed, recommended, and age-appropriate vaccine should be used.For the 2017-18 season, quadrivalent and trivalent influenza vaccines will be available. Inactivated influenza vaccines (IIVs) will be available in trivalent (IIV3) and quadrivalent (IIV4) formulations. Recombinant influenza vaccine (RIV) will be available in trivalent (RIV3) and quadrivalent (RIV4) formulations. Live attenuated influenza vaccine (LAIV4) is not recommended for use during the 2017-18 season due to concerns about its effectiveness against (H1N1)pdm09 viruses during the 2013-14 and 2015-16 seasons. Recommendations for different vaccine types and specific populations are discussed. No preferential recommendation is made for one influenza vaccine product over another for persons for whom more than one licensed, recommended product is available.Updates to the recommendations described in this report reflect discussions during public meetings of ACIP held on October 20, 2016; February 22, 2017; and June 21, 2017. New and updated information in this report includes the following:•Vaccine viruses included in the 2017-18 U.S. trivalent influenza vaccines will be an A/Michigan/45/2015 (H1N1)pdm09-like virus, an A/Hong Kong/4801/2014 (H3N2)-like virus, and a B/Brisbane/60/2008-like virus (Victoria lineage). Quadrivalent influenza vaccines will contain these three viruses and an additional influenza B vaccine virus, a B/Phuket/3073/2013-like virus (Yamagata lineage).• Information on recent licensures and labelling changes is discussed, including licensure of Afluria Quadrivalent (IIV4; Seqirus, Parkville, Victoria, Australia); Flublok Quadrivalent (RIV4; Protein Sciences, Meriden, Connecticut); and expansion of the age indication for FluLaval Quadrivalent (IIV4; ID Biomedical Corporation of Quebec, Quebec City, Quebec, Canada), previously licensed for ≥3 years, to ≥6 months.• Pregnant women may receive any licensed, recommended, age-appropriate influenza vaccine.• Afluria (IIV3; Seqirus, Parkville, Victoria, Australia) may be used for persons aged ≥5 years, consistent with Food and Drug Administration-approved labeling.• FluMist Quadrivalent (LAIV4; MedImmune, Gaithersburg, Maryland) should not be used during the 2017-18 season due to concerns about its effectiveness against influenza A(H1N1)pdm09 viruses in the United States during the 2013-14 and 2015-16 influenza seasons.This report focuses on the recommendations for use of vaccines for the prevention and control of influenza during the 2017-18 season in the United States. A Background Document containing further information and a summary of these recommendations are available at https://www.cdc.gov/vaccines/hcp/acip-recs/vacc-specific/flu.html. These recommendations apply to licensed influenza vaccines used within Food and Drug Administration-licensed indications, including those licensed after the publication date of this report. Updates and other information are available at CDC's influenza website (https://www.cdc.gov/flu). Vaccination and health care providers should check CDC's influenza website periodically for additional information.

Introduction: Varicella vaccines are highly effective at preventing disease, but varicella may occur among vaccinated persons (termed breakthrough varicella). Breakthrough varicella is generally mild, but severe cases have been reported. The objective of this review is to describe severe breakthrough varicella. Areas covered: We conducted a systematic review of articles published during 1974-2016. A total of 34 articles were included in our review: 21 described breakthrough varicella with disseminated varicella-zoster virus (VZV) infection with other organ involvement in addition to skin (none among two-dose vaccinees); 9 described hospitalized breakthrough varicella without mention of other organ involvement in addition to skin (of which 2 reported 4 two-dose vaccinees); and 4 described both. A total of 52-60 unique breakthrough varicella cases with disseminated VZV infection with other organ involvement in addition to skin reported with the following complications, not mutually exclusive: pneumonia (n = 8-9 cases), neurologic (n = 18-24 cases), hematologic (n = 10-11 cases), ocular (n = 5 cases), renal (n = 2 cases), hepatic (n = 3 cases), secondary infection with bacteremia or sepsis (n = 8 cases), and other complication (n = 4 cases). There were 6 cases of fatal breakthrough varicella. Expert commentary: With >31 million doses distributed annually worldwide since 2007, severe breakthrough varicella can occur but they appear to be uncommon.

This report updates the 2015-16 recommendations of the Advisory Committee on Immunization Practices (ACIP) regarding the use of seasonal influenza vaccines (Grohskopf LA, Sokolow LZ, Olsen SJ, Bresee JS, Broder KR, Karron RA. Prevention and control of influenza with vaccines: recommendations of the Advisory Committee on Immunization Practices, United States, 2015-16 influenza season. MMWR Morb Mortal Wkly Rep 2015;64:818-25). Routine annual influenza vaccination is recommended for all persons aged ≥6 months who do not have contraindications. For the 2016-17 influenza season, inactivated influenza vaccines (IIVs) will be available in both trivalent (IIV3) and quadrivalent (IIV4) formulations. Recombinant influenza vaccine (RIV) will be available in a trivalent formulation (RIV3). In light of concerns regarding low effectiveness against influenza A(H1N1)pdm09 in the United States during the 2013-14 and 2015-16 seasons, for the 2016-17 season, ACIP makes the interim recommendation that live attenuated influenza vaccine (LAIV4) should not be used. Vaccine virus strains included in the 2016-17 U.S. trivalent influenza vaccines will be an A/California/7/2009 (H1N1)-like virus, an A/Hong Kong/4801/2014 (H3N2)-like virus, and a B/Brisbane/60/2008-like virus (Victoria lineage). Quadrivalent vaccines will include an additional influenza B virus strain, a B/Phuket/3073/2013-like virus (Yamagata lineage).Recommendations for use of different vaccine types and specific populations are discussed. A licensed, age-appropriate vaccine should be used. No preferential recommendation is made for one influenza vaccine product over another for persons for whom more than one licensed, recommended product is otherwise appropriate. This information is intended for vaccination providers, immunization program personnel, and public health personnel. Information in this report reflects discussions during public meetings of ACIP held on October 21, 2015; February 24, 2016; and June 22, 2016. These recommendations apply to all licensed influenza vaccines used within Food and Drug Administration-licensed indications, including those licensed after the publication date of this report. Updates and other information are available at CDC's influenza website (http://www.cdc.gov/flu). Vaccination and health care providers should check CDC's influenza website periodically for additional information.