Abstract Background In September 2023, the Centers for Disease Control and Prevention’s Advisory Committee on Immunization Practices (ACIP) recommended updated 2023-2024 (monovalent XBB.1.5) COVID-19 vaccines for use in persons ≥6 months for prevention of COVID-19, including severe disease. Understanding how well updated COVID-19 vaccines work in the context of high population immunity due to prior infection, vaccination, or both, is important for future vaccine policy decisions, as well as informing patient/provider discussions, and increasing vaccine confidence. Effectiveness of updated (2023-2024) COVID-19 vaccination against laboratory-confirmed COVID-19-associated emergency department/urgent care encounters and hospitalization among immunocompetent adults aged ≥18 years — VISION Network, September 2023–March 2024 Methods VISION, an electronic health record (EHR)-based network including emergency departments/urgent care clinics (ED/UCs) and hospitals including 6 health systems, uses clinician-ordered testing data to estimate vaccine effectiveness (VE) for respiratory viruses. COVID-19 VE was estimated using the test-negative design, comparing the odds of vaccination with a single updated 2023-2024 COVID-19 vaccine dose between patients who tested positive versus those who tested negative for SARS-CoV-2 by molecular assay, adjusting for potential confounders. Effectiveness of updated 2023–2024 (monovalent XBB.1.5) COVID-19 vaccination against laboratory-confirmed COVID-19–associated hospitalization among immunocompromised adults aged ≥18 years — VISION network, September 2023–March 2024 Results A total of 198,345 ED/UC encounters and 59,777 hospitalizations between September 2023-March 2024 among immunocompetent adults ≥18 years with symptoms of COVID-19 were included. VE against COVID-19-associated ED/UC encounters comparing receipt of an updated dose to no receipt of an updated dose was 50% (95% CI: 46-53%) in the 7-59 days and 0 (95% CI: -14 to 12) in the 120-179 days after receipt of an updated dose (Table 1). VE against COVID-19-associated hospitalization was 50% (95% CI: 44-56%) in the 7-59 days and 23 (95% CI: 2-39) in the 120-179 days after receipt of an updated dose (Table 1). A total of 17,417 hospitalizations among immunocompromised adults ≥18 years with symptoms of COVID-19 were included, with a VE of 38% (95% CI: 23-50%) in the 7-59 days and 14 (95% CI: -33 to 44) in the 120-179 days after receipt of an updated dose after an updated dose (Table 2). Conclusion Receipt of an updated COVID-19 vaccine dose provided protection against COVID-19-associated ED/UC encounters and hospitalizations among immunocompetent and immunocompromised adults, although waning was evident. Disclosures Nicola P. Klein, MD, PhD, GlaxoSmithKline: Grant/Research Support|Merck: Grant/Research Support|Pfizer: Grant/Research Support|Sanofi Pasteur: Grant/Research Support|Seqirus: Grant/Research Support Toan Ong, PhD, Patent Title: Systems and Methods For Record Linkage: PCT/US2018/047961 Patent Title: Systems and Methods For Record Linkage|PCORI: Travel support to attend the PCORI Annual meeting in Washington DC, 2023|Regenstrief Institute: Advisor/Consultant|Regenstrief Institute: Travel support to attend the OHIE 23 meeting in Malawi. Brian E. Dixon, PhD, Elsevier: Honoraria

COVID-19-associated hospitalizations, ICU admissions, and in-hospital deaths averted from 2023 to 2024 COVID19 vaccination from the weeks of October 1, 2023, through April 21, 2024, were estimated via a novel multiplier model that utilized causal inference, conditional probabilities of hospitalization, and correlations between data elements in Monte Carlo simulations. Median COVID-19-associated hospitalizations averted were 68,315 (95 % uncertainty interval [UI] 42,831-97,984), ICU admissions averted were 13,108 (95 % UI 4459-25,042), and in- hospital deaths averted were 5301 (95 % UI 101-14,230). Averted COVID-19-associated burden was highest in adults aged 65 years and older (hospitalizations averted 57,665, 95 % UI 35,442-84,006; ICU admissions averted 10,878, 95 % UI 3104-21,591; in-hospital deaths averted 4779, 95 % UI 0-13,132). Expanding the analytic period to comprise the weeks of September 24, 2023, through August 11, 2024, resulted in 107,197 COVID-19associated hospitalizations averted (95 % UI 80,692-137,643), 18,292 COVID-19-associated ICU admissions averted (95 % UI 10,062-28,436), and 6749 COVID-19-associated in-hospital deaths averted (95 % UI 2077-13,557). Older adults had the highest COVID-19-associated averted burden and potential to reduce burden further through increased vaccine coverage. 2023-2024 COVID-19 vaccinations reduced the burden of COVID19-associated severe disease.

Background:In August 2023, the Centers for Disease Control and Prevention recommended nirsevimab, a long-acting monoclonal antibody, for all U.S. infants aged <8 months entering or born during their first respiratory syncytial virus (RSV) season. Our aim was to estimate nirsevimab effectiveness against RSV-associated emergency department (ED) encounters and hospitalisation among U.S. infants during the 2023-2024 RSV season. Methods:We conducted a test-negative analysis using electronic health record (EHR) data from 6 healthcare systems, including ED encounters and hospitalizations with a diagnosis of RSV-like illness (RLI) during October 8, 2023-March 31, 2024, among infants aged <8 months as of October 1, 2023, or born during the study period. Nirsevimab effectiveness was estimated by comparing children who received nirsevimab with those who did not among RSV-positive and RSV-negative encounters, adjusting for age, race and ethnicity, sex, calendar day, and geographic region and excluding infants whose mother received RSV vaccination during pregnancy. Findings:Among 5039 ED encounters with RLI among infants in their first RSV season, 2045 (41%) were RSV-positive and 446 (9%) received nirsevimab, with a median time since dose of 52 days (interquartile range [IQR]: 27-84 days). Among 1025 hospitalizations with RLI among infants in their first RSV season, 605 (59%) were RSV-positive and 95 (9%) received nirsevimab, with a median time since dose of 48 days (IQR: 24-82 days). Nirsevimab effectiveness was 77% (95% CI: 69%-83%) against RSV-associated ED encounters and 98% (95% CI: 95%-99%) against RSV-associated hospitalisation. Interpretation:Nirsevimab was effective in preventing RSV-associated ED encounters and hospitalisation among infants in their first RSV season, with greatest protection against hospitalisation. However, these estimates reflect a short interval from nirsevimab administration to RLI onset. Since nirsevimab is a passive immunization and concentration is expected to wane over time, it is important to continue monitoring effectiveness to assess effectiveness with increased time since dose. Funding:This work was supported by the Centers for Disease Control and Prevention (contracts 75D30121D12779 to Westat and 75D30123C18039 to Kaiser Foundation Hospitals).

BACKGROUND:During the U.S. COVID-19 Public Health Emergency (PHE), healthcare providers were required to report all administered COVID-19 vaccines in Immunization Information Systems (IIS), a key data source for vaccine effectiveness (VE) evaluations. Expiration of the PHE and commercialization of COVID-19 vaccines raised concerns about IIS data completeness. Parental report is an alternative source of vaccination data but might be inaccurate. METHODS:Using VE surveillance network data during May 2021-October 2023, we compared parent-reported and documented COVID-19 vaccine doses for patients aged 5-18 years admitted to 35 hospitals in 25 states, overall and by case/control status. We calculated percent agreement, kappa, sensitivity, specificity, and positive and negative predictive value (NPV) of parental report. We compared proportions of patients with discordant vaccination history by demographics and incident SARS-CoV-2 infection status. We estimated VE separately using parental report and independently documented sources. RESULTS:Among 3262 patients, agreement between parent-reported and documented COVID-19 vaccination doses was 88 % (kappa = 0.77). Most discordant pairs (346/390) were because of parental over-reporting of doses. Among patients documented as unvaccinated, most (specificity = 90 %) were reported as such by parents; nearly all reported as unvaccinated by parents had no documented vaccination (NPV = 99 %). Discordance decreased with shorter admission-to-interview intervals and varied regionally from 8 % in the Midwest to 16 % in the West. Proportions of discordant reports were similar between patients with and without SARS-CoV-2 infection (11 % vs 13 %). Median days from last vaccine dose to hospital admission was 167 (IQR: 86-288). VE of two doses (99 % original formula) against COVID-19-related hospitalization was 58 % using documented sources and 60 % using parental report. CONCLUSIONS:Parental report of COVID-19 vaccination agreed strongly with documented sources, especially among unvaccinated patients. Despite discrepancies from parental overreporting, VE estimates from both sources were similar. As reliance on parental report increases, reducing admission-to-interview time is important for accurate vaccination history.

During 2023, the Centers for Disease Control and Prevention (CDC) recommended the first respiratory syncytial virus (RSV) immunizations intended for widespread use in the United States to prevent severe RSV illness in infants and older adults. CDC, in collaboration with federal, public health, and academic partners, is conducting evaluations of real-world effectiveness of recommended RSV immunization products in the United States. Similar frameworks for evaluation are being applied to RSV vaccines and nirsevimab, a long-acting preventative monoclonal antibody, to estimate product effectiveness. The overall goal of CDC's RSV immunization effectiveness program is to generate timely and robust evidence through observational studies to inform immunization product policy decisions and other measures related to RSV prevention and control. CDC is evaluating effectiveness through high-quality, well-controlled observational studies leveraging a variety of platforms that provide robust data to inform policy decisions.

Nirsevimab is a long-acting monoclonal antibody that protects infants and young children against severe respiratory syncytial virus (RSV) disease. Children are eligible for one 50 mg dose, one 100 mg dose, or two 100 mg doses of nirsevimab based on age, weight, time of year, maternal vaccination, and risk of severe disease. In winter 2023/2024, we developed a model to project the number of nirsevimab doses needed to immunize all eligible U.S. children during the 2024/2025 season. We grouped all births from March 2023 through March 2025 into weekly cohorts, partitioned those cohorts based on eligibility criteria, and computed eligibility for each partition. In the absence of maternal RSV vaccination, we estimated U.S. children would be eligible to receive 4.3 million nirsevimab doses in 2024/2025, of which 48% would be 100 mg doses. Projections of total eligibility can be used to inform production goals and avoid shortages of nirsevimab.

Background and objectives: In June 2022, the mRNA COVID-19 vaccination was recommended for young children. We examined clinical characteristics and factors associated with vaccination status among vaccine-eligible young children hospitalized for acute COVID-19. Methods: We enrolled inpatients 8 months to <5 years of age with acute community-acquired COVID-19 across 28 US pediatric hospitals from September 20, 2022 to May 31, 2023. We assessed demographic and clinical factors, including the highest level of respiratory support, and vaccination status defined as unvaccinated, incomplete, or complete primary series [at least 2 (Moderna) or 3 (Pfizer-BioNTech) mRNA vaccine doses ≥14 days before hospitalization]. Results: Among 597 children, 174 (29.1%) patients were admitted to the intensive care unit and 75 (12.6%) had a life-threatening illness, including 51 (8.5%) requiring invasive mechanical ventilation. Children with underlying respiratory and neurologic/neuromuscular conditions more frequently received higher respiratory support. Only 4.5% of children hospitalized for COVID-19 (n = 27) had completed their primary COVID-19 vaccination series and 7.0% (n = 42) of children initiated but did not complete their primary series. Among 528 unvaccinated children, nearly half (n = 251) were previously healthy, 3 of them required extracorporeal membrane oxygenation for acute COVID-19 and 1 died. Conclusions: Most young children hospitalized for acute COVID-19, including most children admitted to the intensive care unit and with life-threatening illness, had not initiated COVID-19 vaccination despite being eligible. Nearly half of these children had no underlying conditions. Of the small percentage of children who initiated a COVID-19 primary series, most had not completed it before hospitalization.

BACKGROUND AND OBJECTIVES Respiratory syncytial virus (RSV) causes substantial hospitalization in US infants. The Advisory Committee on Immunization Practices recommended nirsevimab in infants younger than 8 months born during or entering their first RSV season and for children aged 8 to 19 months at increased risk of RSV hospitalization in their second season. This study's objective was to evaluate the cost-effectiveness of nirsevimab in all infants in their first RSV season and in high-risk children in their second season. METHODS We simulated healthcare utilization and deaths from RSV with and without nirsevimab among infants aged 0 to 7 months and those 8 to 19 months old over a single RSV season. Data came from published literature, US Food and Drug Administration approval documents, and epidemiologic surveillance data. We evaluated societal outcomes over a lifetime discounting at 3% and reporting in 2022 US dollars. Sensitivity and scenario analyses identified influential variables. RESULTS We estimated that 107 253 outpatient visits, 38 204 emergency department visits, and 14 341 hospitalizations could be averted each year if half of the US birth cohort receives nirsevimab. This would cost $153 517 per quality-adjusted life year (QALY) saved. Nirsevimab in the second season for children facing a 10-fold higher risk of hospitalization would cost $308 468 per QALY saved. Sensitivity analyses showed RSV hospitalization costs, nirsevimab cost, and QALYs lost from RSV disease were the most influential parameters with cost-effectiveness ratios between cost-saving and $323 788 per QALY saved. CONCLUSIONS Nirsevimab for infants may be cost-effective, particularly among those with higher risks and costs of RSV.

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.

In May 2023, the US Food and Drug Administration (FDA) approved the first vaccines for the prevention of respiratory syncytial virus (RSV)-associated lower respiratory tract disease (LRTD) for use in adults aged ≥60 years: 1 manufactured by GSK (Arexvy)1 and 1 by Pfizer (Abrysvo).2 In July 2023, FDA approved nirsevimab (Beyfortus, Sanofi, and AstraZeneca), a long-acting monoclonal antibody for passive immunization to prevent RSV-associated LRTD among infants and children aged <24 months.3 In August 2023, FDA approved the Pfizer RSV vaccine for pregnant persons, with administration indicated at 32 to 36 weeks' gestation to prevent RSV-associated LRTD and severe LRTD in infants aged <6 months.2 GSK RSV vaccine is not approved for use during pregnancy.1 In August 2023, the Advisory Committee on Immunization Practices and the Centers for Disease Control and Prevention (CDC) recommended nirsevimab for all infants aged <8 months who are born during or entering their first RSV season and for infants and children aged 8 through 19 months entering their second RSV season who are at increased risk for severe RSV disease.4 Administration of either maternal Pfizer RSV vaccine during pregnancy at 32 through 36 weeks' gestation or nirsevimab to the infant is recommended to prevent RSV-associated LRTD in infants, but both are not needed for most infants.5 Pfizer and GSK RSV vaccines are not approved for use in infants and young children.1,2Health care facilities that provide preventive care for children and adults might store and administer Pfizer and GSK RSV vaccines, other routine vaccines, and nirsevimab; thus, the potential exists for Pfizer or GSK RSV vaccines to be administered in error to infants and young children.The Vaccine Adverse Event Reporting System (VAERS) is a national, spontaneous reporting (passive surveillance) system comanaged by CDC and FDA.6 VAERS reports are classified as serious if any of the following are reported: hospitalization, prolongation of hospitalization, life-threatening illness, permanent disability, congenital anomaly or birth defect, or death.7 To assess vaccine administration errors of Pfizer or GSK RSV vaccine use in infants and young children aged <2 years, the VAERS database was searched for reports of children aged <24 months who received an RSV vaccine, and a text string search was conducted for the words "infant," "child," "newborn," "neonate," "pediatric," "month," and "peds" within the fields' symptom text or laboratory data for those reports where age was not provided. This activity was reviewed by CDC and was conducted consistent with applicable federal law and CDC policy.8From August 21, 2023, to March 18, 2024, the VAERS database included 34 reports of administration errors indicating that either Pfizer or GSK RSV vaccine had been administered to children aged <2 years; 31 were in infants aged <8 months (Table 1). For 21 reports, a family medicine practice was the vaccination location. Twenty-seven reports involved Pfizer and 7 involved GSK RSV vaccine. Twenty-seven reports included no adverse health events. Seven reports described at least 1 adverse health event, including a serious report of an infant with a history of congenital heart disease hospitalized for cardiorespiratory arrest within 24 hours after receipt of GSK RSV vaccine in addition to routine childhood vaccines (Table 1). Six reports described injection site or systemic reactions (eg, irritability) after administration of Pfizer or GSK RSV vaccine.This review found infrequent reports of Pfizer and GSK RSV vaccines administered to infants and young children aged <2 years in error. VAERS limitations include reporting biases (over- or underreporting) and inconsistency in quality and completeness of reports.6 Health care providers should not administer Pfizer or GSK RSV vaccine to infants and young children.1,2,5 Administration errors are preventable with proper education and training, ordering only products that are approved for the patient population a facility serves, electronic health record alerts or warnings, close attention to labeling, storage best practices, and other preventive measures.9 To increase awareness and help prevent these vaccine administration errors, CDC is working to educate health care providers administering vaccinations and nirsevimab to young children aged <2 years.10 Health care providers are encouraged to report vaccination errors to VAERS,11 including those involving Pfizer or GSK RSV vaccines.12 CDC and FDA will continue to monitor VAERS for these administration errors.6We thank Elaine Miller, Tom Shimabukuro, John Su, Hannah Brown, and Carol Ennulat, CDC; Immunization Safety Office, CDC; Meghna Alimchandani and Narayan Nair; Center for Biologics Evaluation and Research, FDA; and General Dynamics Information Technology.

BACKGROUND:On September 2, 2022, bivalent COVID-19 mRNA vaccines, were recommended to address reduced effectiveness of COVID-19 monovalent vaccines during SARS-CoV-2 Omicron variant predominance. METHODS:Using national pharmacy-based SARS-CoV-2 testing program data from January 15 to September 11, 2023, this test-negative, case-control design study assessed bivalent COVID-19 vaccine effectiveness (VE) against symptomatic infection. RESULTS:VE against symptomatic infection of a bivalent dose between 2 weeks and 1 month after bivalent vaccination ranged from 46% (95% CI: 38%-52%) for those aged ≥ 65 years to 61% (95% CI 41%-75%) for those aged 12-17 years. CONCLUSION:Bivalent vaccines protected against symptomatic infection. However, effectiveness waned over time, emphasizing the need to stay up to date with COVID-19 vaccination.

BACKGROUND:Respiratory syncytial virus vaccines first recommended for use during 2023 were efficacious against lower respiratory tract disease in clinical trials. Limited real-world data regarding respiratory syncytial virus vaccine effectiveness are available. To inform vaccine policy and address gaps in evidence from the clinical trials, we aimed to assess the effectiveness against respiratory syncytial virus-associated hospitalisations and emergency department encounters among adults aged at least 60 years. METHODS:We conducted a test-negative design analysis in an electronic health records-based network in eight states in the USA, including hospitalisations and emergency department encounters with respiratory syncytial virus-like illness among adults aged at least 60 years who underwent respiratory syncytial virus testing from Oct 1, 2023, to March 31, 2024. Respiratory syncytial virus vaccination status at the time of the encounter was derived from electronic health record documentation, state and city immunisation registries, and, for some sites, medical claims. Vaccine effectiveness was estimated by immunocompromise status, comparing the odds of vaccination among respiratory syncytial virus-positive case patients and respiratory syncytial virus-negative control patients, and adjusting for age, race and ethnicity, sex, calendar day, social vulnerability index, number of underlying non-respiratory medical conditions, presence of respiratory underlying medical conditions, and geographical region. FINDINGS:Among 28 271 hospitalisations for respiratory syncytial virus-like illness among adults aged at least 60 years without immunocompromising conditions, vaccine effectiveness was 80% (95% CI 71-85) against respiratory syncytial virus-associated hospitalisations, and vaccine effectiveness was 81% (52-92) against respiratory syncytial virus-associated critical illness (ICU admission or death, or both). Among 8435 hospitalisations for respiratory syncytial virus-like illness among adults with immunocompromising conditions, vaccine effectiveness was 73% (48-85) against associated hospitalisation. Among 36 521 emergency department encounters for respiratory syncytial virus-like illness among adults aged at least 60 years without an immunocompromising condition, vaccine effectiveness was 77% (70-83) against respiratory syncytial virus-associated emergency department encounters. Vaccine effectiveness estimates were similar by age group and product type. INTERPRETATION:Respiratory syncytial virus vaccination was effective in preventing respiratory syncytial virus-associated hospitalisations and emergency department encounters among adults aged at least 60 years in the USA during the 2023-24 respiratory syncytial virus season, which was the first season after respiratory syncytial virus vaccine was approved. FUNDING:The Centers for Disease Control and Prevention.

COVID-19 remains an important public health threat, despite overall decreases in COVID-19-related severe disease since the start of the COVID-19 pandemic. COVID-19-associated hospitalization rates remain higher among adults aged ≥65 years relative to rates in younger adults, adolescents, and children; during October 2023-January 2024, 67% of all COVID-19-associated hospitalizations were among persons aged ≥65 years. On September 12, 2023, CDC's Advisory Committee on Immunization Practices (ACIP) recommended updated (2023-2024 Formula) COVID-19 vaccination with a monovalent XBB.1.5-derived vaccine for all persons aged ≥6 months to protect against severe COVID-19-associated illness and death. Because SARS-CoV-2 continues to circulate throughout the year, and because of the increased risk for COVID-19-related severe illness in persons aged ≥65 years, the protection afforded by updated vaccines against JN.1 and other currently circulating variants, and the expected waning of vaccine-conferred protection against disease, on February 28, 2024, ACIP recommended all persons aged ≥65 years receive 1 additional dose of the updated (2023-2024 Formula) COVID-19 vaccine. Implementation of these recommendations is expected to enhance immunity that might have waned and decrease the risk for severe COVID-19-associated outcomes, including death, among persons aged ≥65 years.

COVID-19 vaccination provides additional protection against severe COVID-19-associated illness and death. Since September 2023, 2023-2024 Formula monovalent XBB.1-strain COVID-19 vaccines have been recommended for use in the United States for all persons aged ≥6 months. However, SARS-CoV-2 continues to evolve, and since winter 2023-2024, Omicron JN.1 lineage strains of SARS-CoV-2, including the JN.1 strain and the KP.2 strain, have been widely circulating in the United States. Further, COVID-19 vaccine effectiveness is known to wane. On June 27, 2024, the Advisory Committee on Immunization Practices (ACIP) recommended 2024-2025 COVID-19 vaccination with a Food and Drug Administration (FDA)-approved or authorized vaccine for all persons aged ≥6 months. On August 22, 2024, FDA approved the 2024-2025 COVID-19 vaccines by Moderna and Pfizer-BioNTech (based on the KP.2 strain) for use in persons aged ≥12 years and authorized these vaccines for use in children aged 6 months-11 years under Emergency Use Authorization (EUA). On August 30, 2024, FDA authorized 2024-2025 COVID-19 vaccine by Novavax (based on the JN.1 strain) for use in persons aged ≥12 years under EUA. ACIP will continue to evaluate new evidence as it becomes available and will update recommendations as needed.

On September 12, 2023, CDC's Advisory Committee on Immunization Practices recommended updated 2023-2024 (updated) COVID-19 vaccination with a monovalent XBB.1.5-derived vaccine for all persons aged ≥6 months to prevent COVID-19, including severe disease. During fall 2023, XBB lineages co-circulated with JN.1, an Omicron BA.2.86 lineage that emerged in September 2023. These variants have amino acid substitutions that might increase escape from neutralizing antibodies. XBB lineages predominated through December 2023, when JN.1 became predominant in the United States. Reduction or failure of spike gene (S-gene) amplification (i.e., S-gene target failure [SGTF]) in real-time reverse transcription-polymerase chain reaction testing is a time-dependent, proxy indicator of JN.1 infection. Data from the Increasing Community Access to Testing SARS-CoV-2 pharmacy testing program were analyzed to estimate updated COVID-19 vaccine effectiveness (VE) (i.e., receipt versus no receipt of updated vaccination) against symptomatic SARS-CoV-2 infection, including by SGTF result. Among 9,222 total eligible tests, overall VE among adults aged ≥18 years was 54% (95% CI = 46%-60%) at a median of 52 days after vaccination. Among 2,199 tests performed at a laboratory with SGTF testing, VE 60-119 days after vaccination was 49% (95% CI = 19%-68%) among tests exhibiting SGTF and 60% (95% CI = 35%-75%) among tests without SGTF. Updated COVID-19 vaccines provide protection against symptomatic infection, including against currently circulating lineages. CDC will continue monitoring VE, including for expected waning and against severe disease. All persons aged ≥6 months should receive an updated COVID-19 vaccine dose.

COVID-19 remains an important cause of morbidity and mortality, especially among adults aged >= 65 years and persons with moderate or severe immunocompromise; these persons are among those at highest risk for severe disease from COVID-19. On June 27, 2024, the Advisory Committee on Immunization Practices (ACIP) recommended 2024-2025 COVID-19 vaccination for all persons aged >= 6 months to target currently circulating strains of SARS-CoV-2 and provide additional protection against severe COVID-19. Because SARS-CoV-2 circulates year-round and immunity from vaccination wanes, on October 23, 2024, ACIP recommended a second 2024- 2025 COVID-19 vaccine dose for all adults aged >= 65 years and for persons aged 6 months-64 years with moderate or severe immunocompromise, 6 months after their last dose of 2024- 2025 COVID-19 vaccine (minimum interval = 2 months). Further, ACIP recommended that persons aged >= 6 months who are moderately or severely immunocompromised may receive additional doses of 2024-2025 COVID-19 vaccine (i.e., a total of >= 3 doses of 2024-2025 COVID-19 vaccine) based on shared clinical decision-making. Staying up to date with COVID-19 vaccination is recommended to decrease the risk for severe COVID-19, especially among adults aged >= 65 years and persons with moderate or severe immunocompromise.

BACKGROUND AND OBJECTIVES Respiratory syncytial virus (RSV) commonly causes hospitalization among US infants. A maternal vaccine preventing RSV in infants, RSV bivalent prefusion F maternal vaccine (RSVpreF), was approved by the US Food and Drug Administration and recommended by the Advisory Committee on Immunization Practices. Our objective was to evaluate the health benefits and cost-effectiveness of vaccinating pregnant persons in the United States using RSVpreF. METHODS We simulated RSV infection and disease with and without seasonal RSVpreF vaccination in half of the pregnant persons in the annual US birth cohort during weeks 32 through 36 of gestation. Model inputs came from peer-reviewed literature, Food and Drug Administration records, and epidemiological surveillance databases. The results are reported using a societal perspective in 2022 US dollars for a 1-year time frame, discounting future health outcomes and costs at 3%. Sensitivity and scenario analyses were performed. RESULTS Year-round maternal vaccination with RSVpreF would prevent 45 693 outpatient visits, 15 866 ED visits, and 7571 hospitalizations among infants each year. Vaccination had a societal incremental cost of $396 280 per quality-adjusted life-year (QALY) saved. Vaccination from September through January cost $163 513 per QALY saved. The most influential inputs were QALYs lost from RSV disease, the cost of the vaccine, and RSV-associated hospitalization costs; changes in these inputs yielded outcomes ranging from cost-saving to $800 000 per QALY saved. CONCLUSIONS Seasonal maternal RSV vaccination designed to prevent RSV lower respiratory tract infection in infants may be cost-effective, particularly if administered to pregnant persons immediately before or at the beginning of the RSV season.

Background: Bivalent mRNA vaccines were recommended since September 2022. However, coverage with a recent vaccine dose has been limited, and there are few robust estimates of bivalent VE against symptomatic SARS-CoV-2 infection (COVID-19). We estimated VE of a bivalent mRNA vaccine dose against COVID-19 among eligible U.S. healthcare personnel who had previously received monovalent mRNA vaccine doses. Methods: We conducted a case-control study in 22 U.S. states, and enrolled healthcare personnel with COVID-19 (case-participants) or without COVID-19 (control-participants) during September 2022-May 2023. Participants were considered eligible for a bivalent mRNA dose if they had received 2-4 monovalent (ancestral-strain) mRNA vaccine doses, and were >= 67 days after the most recent vaccine dose. We estimated VE of a bivalent mRNA dose using conditional logistic regression, accounting for matching by region and four-week calendar period. We adjusted estimates for age group, sex, race and ethnicity, educational level, underlying health conditions,

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.

In September 2023, CDC's Advisory Committee on Immunization Practices recommended updated 2023-2024 (monovalent XBB.1.5) COVID-19 vaccination for all persons aged ≥6 months to prevent COVID-19, including severe disease. As with past COVID-19 vaccines, additional doses may be considered for persons with immunocompromising conditions, who are at higher risk for severe COVID-19 and might have decreased response to vaccination. In this analysis, vaccine effectiveness (VE) of an updated COVID-19 vaccine dose against COVID-19-associated hospitalization was evaluated during September 2023-February 2024 using data from the VISION VE network. Among adults aged ≥18 years with immunocompromising conditions, VE against COVID-19-associated hospitalization was 38% in the 7-59 days after receipt of an updated vaccine dose and 34% in the 60-119 days after receipt of an updated dose. Few persons (18%) in this high-risk study population had received updated COVID-19 vaccine. All persons aged ≥6 months should receive updated 2023-2024 COVID-19 vaccination; persons with immunocompromising conditions may get additional updated COVID-19 vaccine doses ≥2 months after the last recommended COVID-19 vaccine.