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: Persons with end stage kidney disease (ESKD) on dialysis are at high risk for severe COVID-19 disease. In September 2023, 2023-2024 COVID-19 vaccination was recommended in the United States for all persons aged ≥6 months. Due to possible immune dysfunction, advanced age, and high prevalence of additional underlying conditions, including immunocompromising conditions, among individuals with ESKD, reduced vaccine effectiveness (VE) is a concern. Understanding effectiveness of 2023-2024 COVID-19 vaccine among persons with ESKD can inform COVID-19 vaccine recommendations for this population. METHODS: A retrospective cohort investigation was conducted among Medicare fee-for-service beneficiaries aged ≥18 years with ESKD receiving dialysis using Medicare enrollment and claims records. Follow-up began on September 17, 2023, and continued until the earliest occurrence of claim for a COVID-19-associated outcome, other censoring event, or end of follow-up. A marginal structural Cox model was used to estimate VE (calculated as [1 - hazard ratio]*100 %), interpreted as the benefit of 2023-2024 COVID-19 vaccination compared with no 2023-2024 vaccine dose. VE was estimated by presence of additional immunocompromising conditions, age group, and time since vaccination. RESULTS: During September 17, 2023 - April 13, 2024, 17,749/112,250 (16 %) Medicare beneficiaries aged ≥18 years with ESKD without additional immunocompromising conditions received a 2023-2024 COVID-19 vaccine dose, with a maximum 209 days of follow-up since vaccination. During the follow-up period 6539 medically attended COVID-19 events, including 3605 COVID-19-associated hospitalizations, 789 COVID-19-associated deaths, and 896 COVID-19-associated thromboembolic events, were recorded. VE against COVID-19-associated hospitalization was 55 % (95 % confidence interval [CI]: 42 % - 65 %) at 7-59 days after vaccination and 47 % (95 % CI: 35 % - 57 %) at ≥60 days after vaccination. VE against COVID-19-associated death was 71 % (95 % CI: 46 % - 84 %) at 7-59 days after vaccination and 51 % (95 % CI: 24 % - 69 %) ≥60 days after vaccination. VE against COVID-19-associated thromboembolic events was 44 % (95 % CI, 24 %, 59 %). CONCLUSIONS: The 2023-2024 COVID-19 vaccines provided protection against COVID-19-associated hospitalization, death, and thromboembolic events among adults with ESKD. These data support the recommendation that adults with ESKD receive the updated COVID-19 vaccine.

During the 2023-2024 respiratory syncytial virus (RSV) season, vaccination was recommended for adults ≥60 years based on shared clinical decision-making with their healthcare providers. We examined RSV vaccine uptake and characteristics associated with uptake among age-eligible Kaiser Permanente Southern California (KPSC) patients. Our study cohort included all patients ≥60 years from September 23, 2023 (i.e., date RSV vaccination first became available at KPSC; N = 1,003,132) to April 9, 2024 (i.e., end of local RSV season). To identify sociodemographic and clinical characteristics associated with RSV vaccination, we used multivariable robust Poisson regression to estimate the adjusted relative risk (aRR) and 95 % CI. Overall, 7.6 % of patients were vaccinated for RSV. In multivariable regression analyses, those aged 70-79.9 years (aRR: 1.36; 95 % CI: 1.34-1.39) and aged ≥80 years (aRR: 1.35; 95 % CI: 1.32-1.38) were more likely to be vaccinated, compared with those aged 60-69.9 years. Compared with Non-Hispanic White patients, Asian (aRR: 0.95; 95 % CI: 0.93-0.97), Hispanic (aRR: 0.52; 95 % CI: 0.51-0.54), Non-Hispanic Black (aRR: 0.69; 95 % CI: 0.67-0.71), Pacific Islander (aRR: 0.91; 95 % CI: 0.84-0.98), and Native American or Alaska Native (aRR: 0.80; 95 % CI: 0.70-0.92) patients were less likely to be vaccinated. Those in higher neighborhood deprivation quartiles were less likely to be vaccinated (Q2: aRR: 0.86; 95 % CI: 0.85-0.88; Q3: aRR: 0.77; 95 % CI: 0.76-0.79; and Q4: aRR: 0.67; 95 % CI: 0.65-0.68), compared with those in the lowest deprivation quartile. We found low vaccination uptake and identified disparities in vaccination that might exacerbate existing disparities in RSV infection and severe RSV disease among certain populations. CDC's ACIP recently updated their recommendations for all adults 75+ years, and this might begin to address these disparities.

Vaccination is an effective preventive strategy against influenza. Kyrgyzstan introduced a comprehensive influenza vaccination program in 2013 and has collaborated with the Task Force for Global Health since 2017 to expand vaccination coverage. In 2023, an influenza vaccine post-introduction evaluation was conducted to identify strengths and weaknesses in the influenza vaccination program and to identify measures for improvement. Site visits were conducted across six regions of the country and interviews were conducted with national, regional and district staff, health facility staff, and individuals from priority populations for influenza vaccination using standardized questionnaires. Two major challenges identified in this evaluation were the inadequate supply of influenza vaccine to cover the priority groups and the low acceptance and uptake of influenza vaccine among pregnant people. These findings are important as they can inform targeted strategies and policy updates to increase influenza vaccine implementation and uptake in Kyrgyzstan.

BACKGROUND: The African Region Monitoring Vaccine Effectiveness network (AFRO-MoVE) was established by the World Health Organization Regional Office for Africa in March 2021 to support implementation of COVID-19 vaccine effectiveness studies in the region. OBJECTIVES: Primary goals of the evaluation were to assess how AFRO-MoVE addressed its objectives supporting regional vaccine effectiveness (VE) studies, to describe challenges and opportunities, and make recommendations to strengthen future efforts related to regional VE research. METHODS: From September 2023 through June 2024, a mixed-methods approach was employed to synthesize information from: (1) documentation provided by AFRO-MoVE; (2) a standardized study review tool; (3) an electronic stakeholder survey; and (4) a series of key informant interviews. Data were collected and exported via REDCap and summarized using Microsoft Excel. Thematic analysis was used to analyse the qualitative data. Perceived challenges were summarized together with perceived support by the network in addressing each challenge. RESULTS: AFRO-MoVE provided support to ten VE studies, including support for protocol development, study implementation, data management, and analysis, while also facilitating knowledge exchange and experience sharing among study implementers. While respondents reported strengthened capacity for VE studies at the national and regional levels in these areas, enrollment of SARS-CoV-2 positive cases was challenging, due to a decline in reported cases in network countries in mid-2022, when many studies were launched. These challenges contributed to a lack of published VE estimates from network study sites in time to inform vaccine policy. CONCLUSION: AFRO-MoVE technical assistance and financial support was viewed positively by network members and contributed to increased capacity for conducting VE studies in the region. Publication of study results would further bolster the impact of the network. These finding underscore opportunities to enhance capacity for rapid VE generation and support preparedness for future pandemics.

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.

Understanding vaccine uptake and related factors among health care workers is critical to successful vaccination programs. A cross-sectional survey was conducted in central, provincial, district hospitals and health centers among health workers in Lao People's Democratic Republic (PDR) in November 2023 to assess health workers' experience with influenza and COVID-19 vaccination, vaccination uptake, intended uptake, and intention to recommend both vaccinations to patients in the future. Logistic regression was used to identify factors associated with these practices. Among 1228 surveyed health workers in six provinces, 55 % were nurses, assistant nurses, or midwives; 32 % were doctors or assistant doctors; and 14 % had other occupations. Overall, 77 % of respondents were female, and the median age was 34 years (interquartile range 29-42 years). Current influenza vaccination and receipt of COVID-19 booster doses were 70 % (95 % confidence interval [CI]: 62-78 %) and 90 % (95 % CI: 87-92 %), respectively. If vaccines were available for free in the future, approximately 94 % and 92 % of health workers would receive influenza and COVID-19 vaccination, respectively. Nearly all health workers would recommend influenza (98 %) and COVID-19 (95 %) vaccination to their patients. Health workers who had received influenza vaccination prior to the COVID-19 pandemic were more likely to have received current influenza vaccination (adjusted odds ratio [aOR], 95 % CI: 3.7, 2.8-4.9) and to intend to receive influenza vaccination in the future (aOR 2.7, 95 % CI: 1.1-6.8). Health workers who were vaccinated for influenza in the current season were more likely to receive COVID-19 booster doses and to intend to receive future booster doses (aOR, 95 % CI: 2.2, 1.3-3.7 and 2.5, 1.2-5.1, respectively). Intention to recommend influenza vaccination to patients was associated with the intention to recommend COVID-19 vaccination to patients, and vice versa. High acceptance for influenza and COVID-19 vaccination among health workers can support a successful vaccination program in Lao PDR.

BACKGROUND: To generate COVID-19 vaccine safety data in Nigeria, passive reporting was supplemented with cohort event monitoring (CEM), an active surveillance system. We described reactogenicity within 7 days and adverse events up to 3 months after each AstraZeneca or Moderna COVID-19 vaccine dose while assessing the feasibility of implementing CEM in a low- to middle-income country (LMIC) during a mass vaccination campaign. METHODS: Participants were aged ≥18 years with access to mobile phones who received the first dose of an authorized COVID-19 vaccine from participating health facilities in 6 states of Nigeria during September and October 2021. Data collectors interviewed participants via phone on days 0, 3, 7, and thereafter every 7 days for 3 months. The same schedule was restarted if a participant received a second vaccine dose. Proportions of participant-reported adverse events following COVID-19 vaccine receipt were calculated. Investigation and causality assessment were conducted on deaths using the World Health Organization causality guidelines. RESULTS: We enrolled 12,317 participants (AstraZeneca 6990; Moderna 5327); 6167/6990 (88.2 %) AstraZeneca and 4879/5327 (91.6 %) Moderna recipients completed a follow-up interview days 0-7 after the first dose; among them, 2685/6167 (43.5 %) AstraZeneca and 3533/4879 (72.4 %) Moderna recipients reported local reactions and 2456/6167 (39.8 %) AstraZeneca and 2087/4879 (42.8 %) Moderna recipients reported systemic reactions. Overall, 3891/6990 (55.7 %) AstraZeneca and 3978/5327 (72.8 %) Moderna recipients received a second dose of COVID-19 vaccine, among whom 897/3891 (23 %) AstraZeneca and 1979/3978 (49.7 %) Moderna recipients reported local reactions and 727/3891 (18.7 %) AstraZeneca and 1680/3978 (42.2 %) Moderna recipients reported systemic reactions. Among all enrolled, 11 died; there was no evidence to suggest any deaths were vaccine-related. CONCLUSIONS: No unexpected patterns of adverse events were detected, providing additional data on the safety of these COVID-19 vaccines in Nigerian adults. We demonstrated that implementing CEM was feasible and may be valuable for safety monitoring of vaccines introduced in LMICs.

INTRODUCTION: Data about healthcare workers' (HCW) willingness to accept and recommend seasonal influenza vaccination in countries without influenza vaccination programs are limited. METHODS: We conducted a cross-sectional survey in 7 of the 47 counties in Kenya to examine HCW's knowledge and perceptions of seasonal influenza disease and vaccination. We aimed to enroll all HCW who deliver clinical services directly or peripherally to patients from 5 health facilities in each county. We used chi-square tests and mixed effects logistic regression to identify variables associated with HCW's willingness to accept and recommend seasonal influenza vaccination. RESULTS: From May-June 2018, we enrolled 2035 HCW, representing 49.0 % of targeted respondents from 35 facilities. Most HCW (82.1 %) were from public health facilities. Among the HCW who had heard of seasonal influenza, 87.3 % (1420/1627) believed it can cause severe illness. Most HCW (1076/1209; 89.0 %) were willing to receive a seasonal influenza vaccine if it was recommended for them and provided for free, and 91.4 % (1441/1576) would vaccinate or recommend vaccination to their patients if vaccine was available. Only 17.6 % (213/1212) reported having ever received a seasonal influenza vaccine. HCW who believed that influenza could cause severe illness (aOR 1.8; 95 % CI 1.0-3.2) and that people around them would be better protected from influenza illness if HCW are vaccinated (aOR 3.1; 95 % CI 2.0-4.9) were more likely to report willingness to accept vaccination. HCW from private health facilities (aOR 2.2; 95 % CI 1.3-6.4), and those who believed that people around them are better protected if HCW are vaccinated (aOR 3.5; 95 % CI 2.2-5.8) were more likely to report willingness to vaccinate or recommend vaccination to patients. CONCLUSION: Our findings suggest favorable attitudes among HCW towards seasonal influenza vaccination, many of whom are motivated by the desire to protect the health of others around them.

A World Health Organization (WHO) Defeating Meningitis Symposium took place as part of the 3rd International Symposium on Streptococcus agalactiae disease (ISSAD) conference which was held in Rio de Janeiro, Brazil, from October 16-18, 2023. The symposium highlighted WHO's Defeating meningitis by 2030 global road map focusing on Group B Streptococcus (GBS) meningitis and provided an overview of the meningitis burden and main challenges faced to tackle the disease across the Americas, Africa, and Asia.

INTRODUCTION: There is limited information about vaccine-preventable disease (VPD) surveillance cost. To address this gap, retrospective micro-costing studies of pre-COVID-19 pandemic VPD surveillance were conducted in Nepal and Ethiopia. Based on these evaluations-the sole cost evaluations on comprehensive VPD surveillance-this article provides methodological considerations and recommendations for other countries planning to conduct VPD surveillance costing studies to inform planning and budgeting. METHODS: The methods used for each study were systematically compared by key themes: costing perspective, cost categories, costing approach, allocation of shared costs, sampling criteria, extrapolation strategies, data collection, and analytic adjustments. For each theme, investigators identified methodologic challenges and potential strategies to address them, compared study methodologies to surveillance costing guidelines, and recommended practices for future such studies. RESULTS: The studies used similar perspectives and VPD inclusion criteria. Costs in Nepal were collected and analyzed by a subset of surveillance core and support functions, whereas the Ethiopia study categorized costs using surveillance support functions from the Global Strategy on Comprehensive VPD Surveillance. A mix of random and purposive sampling of surveillance sites was used in both studies. Surveillance sites were selected considering the strata of interest at each administrative level. Results from both studies were extrapolated country-wide using sampling weights and assumptions about the representativeness of purposively sampled units. DISCUSSION: The review highlighted potential methodologic tradeoffs in utility and precision of results based on the lessons learned from two country VPD surveillance cost studies. The advantages of collecting and using cost estimates by VPD surveillance core versus support function for program budgeting for varied audiences should be explored in future studies. Sampling strategies should be developed with consideration for the precision needed for the intended use of costing results. The resulting recommendations can improve and standardize the conduct and interpretation of future such studies.

BACKGROUND: Uzbekistan, a highly endemic country for hepatitis B virus (HBV), introduced infant vaccination with hepatitis B vaccine (HepB) in 2001. Since 2002, it had ≥90 % reported immunization coverage for ≥3 doses of HepB (HepB3) and the birth dose (HepB-BD). However, the impact of HepB vaccination and the progress towards achieving the regional hepatitis B control and global viral hepatitis B elimination goals had not been assessed. METHODS: To determine current HBsAg prevalence among children in Uzbekistan, in 2022, we conducted a nationwide serosurvey among schoolchildren (grades 1-3) using a stratified, multi-stage cluster design. Participants' basic demographics and HepB immunization information were obtained. Blood specimens were tested for HBsAg using a WHO-prequalified rapid test (Bioline HBsAg WB, Abbott Diagnostics). Samples with positive and indeterminate results were tested for HBsAg by ELISA (Murex HBsAg Version3, Diasorine). Weighted proportions and adjusted 95 % confidence intervals (CI) were calculated. RESULTS: Of 4119 children enrolled in 148 schools, blood was collected from 3753 (91.1 %) and immunization data were available for 3833 (93.3 %). National HBsAg prevalence was 0.20 % (adjusted 95 % CI, 0.09 %-0.38 %). Among children with available immunization data, 97.7 % (97.2 %-98.1 %) received ≥3 HepB doses and 94.9 % (94.1 %-95.5 %) received HepB-BD, including timely HepB-BD in 93.7 % (92.9 %-94.5 %). CONCLUSIONS: The survey demonstrated that Uzbekistan has met the <0.5 % European regional HBsAg seroprevalence target and has made substantial progress towards meeting the <0.1 % HBsAg seroprevalence target for the elimination of HBV mother to-child transmission (MTCT). Based on these findings and ≥ 90 % HepB-BD and HepB3 coverage, in 2023, Uzbekistan was validated as having achieved the regional hepatitis B control goal. To achieve the elimination of MTCT of HBV, additional interventions, including improving antenatal screening for HBsAg, providing antiviral treatment of eligible HBsAg-positive pregnant women and hepatitis B immunoglobulin to infants born to HBsAg-positive mothers, should be considered.

BACKGROUND: The underlying causes for lower rotavirus vaccine effectiveness (VE) in high-child-mortality settings are not well understood. Uganda introduced the human monovalent G1P[8] rotavirus vaccine (Rotarix) in June 2018. We determined the effectiveness of Rotarix against rotavirus diarrhea requiring hospital care among Ugandan children. METHODS: We compared the vaccination status of children with laboratory-confirmed rotavirus (cases) and non-rotavirus (controls) diarrhea who were age-eligible to receive Rotarix and admitted to 3 hospitals in Uganda October 2018-December 2022. VE ([1-odds ratio of vaccination among cases and controls] x 100]) was calculated using unconditional logistic regression adjusting for age, birth month-year, and hospital. RESULTS: Among 187 cases and 622 controls, respectively, 93 % (173/187) and 93 % (579/622) had received ≥1 doses of Rotarix. Adjusted full-series (2 dose) VE against rotavirus diarrhea was 29 % (95 % confidence interval: -37 %-63 %) in children 4-59 months of age. Two-dose VE was 62 % (9 %-84 %) in infants 4-11 months of age and - 69 % (-401 %-43 %) in children 12-59 months of age (P = 0.20). VE against strains partially-heterotypic to the vaccine strain (including G3P[8], the most common curculating genotype) was 59 % (1 %-83 %). CONCLUSIONS: Routine Rotarix vaccination was effective in preventing hospital visits for rotavirus diarrhea among Ugandan infants, although protection was not sustained after the first year of life. Protection was demonstrated against partially heterotypic rotavirus strains. These results support the continued use of rotavirus vaccines in Uganda. Additional studies are needed to understand the lower rotavirus VE seen in Uganda and other high-mortality settings.

BACKGROUND: Streptococcus pneumoniae is an important cause of pneumonia, sepsis, and meningitis, which are leading causes of child mortality. Pneumococcal conjugate vaccines (PCVs) protect against disease and nasopharyngeal colonization with vaccine serotypes, reducing transmission to and among unvaccinated individuals. Mozambique introduced 10-valent PCV (PCV10) in 2013. In 2017-2019, 13-valent PCV (PCV13) replaced PCV10, and in September 2019 the schedule changed from three primary doses to two primary doses and a booster; the booster-containing schedule may increase indirect effects. We examined pneumococcal carriage in Mozambique to establish a baseline for estimating the impact of policy changes and to estimate the long-term impact of PCV10 in children aged <5 years. METHODS: We calculated prevalence of carriage of PCV10 serotypes and the 3 additional PCV13 serotypes ('PCV13-unique') among children aged <5 years and their household members in southern Mozambique, between October 2018 and July 2019. Nasopharyngeal swabs were cultured, and isolates underwent Quellung serotyping. For children, we compared these "long-term post-PCV10" data with prior surveys ("pre-PCV" (2012-2013) and "post-PCV10" (2015-2016)) that used the same methods. RESULTS: In 2018-2019, among 1319 children aged under five years, 1064 (80.7 %) were colonized with pneumococcus, among 614 children aged 5- < 18 years, 355 (57.8 %) were colonized, and among 804 adults (aged ≥18 years), 285 (35.4 %) were colonized. The most frequently observed serotypes were 19 A (n = 154, 8.5 % of isolates) and 6 A (n = 107, 5.9 %), both PCV13-unique serotypes. Overall carriage prevalence among children under five years remained stable at approximately 80 % across the carriage studies conducted between 2012 and 2019; between 2015 and 2016 and 2018-2019, the prevalence of PCV10-type carriage declined from 17.7 % to 10.1 %. CONCLUSIONS: Despite substantial declines in PCV10-type carriage initially following vaccine introduction, the continued circulation of PCV10 serotypes and relative high prevalence of PCV13-unique serotypes underscore the need to understand the impact of policy changes on pneumococcus transmission.

OBJECTIVES: Economic models assessing vaccinations commonly assume that inflation-adjusted vaccine costs are constant over time. This study assessed this assumption using historical vaccine cost data. METHODS: Private sector and CDC contracted vaccine cost data (2001-2023) were collected from the CDC Vaccine Price List and converted to US$2023 to adjust for inflation. Trends in inflation-adjusted costs were described, and the annual percent changes in costs were calculated for each vaccine. RESULTS: Changes in cost varied by vaccine. The average inflation-adjusted private sector costs increased by 0.9 % (IQR: -0.4 %-2.6 %) and 1.4 % (IQR: -0.4 %-3.2 %) annually among pediatric and adult vaccines, respectively, while CDC contracted costs increased by 0.9 % (IQR: 0.2 %-1.2 %) and 1.0 % (IQR: -0.8 %-2.1 %) annually among pediatric and adult vaccines, respectively. CONCLUSIONS: Inflation-adjusted vaccine costs increased on average since 2001, highlighting limitations of constant cost assumptions. These findings can inform cost-effectiveness analyses of multi-year vaccination programs and policies.

INTRODUCTION: Pandemic influenza vaccine development focuses on the hemagglutinin (HA) antigen for potency and immunogenicity. Antibody responses targeting the neuraminidase (NA) antigen, or the HA stalk domain have been implicated in protection against influenza. Responses to the NA and HA-stalk domain following pandemic inactivated influenza are not well characterized in humans. MATERIAL AND METHODS: In a series of clinical trials, we determine the vaccines' NA content and demonstrate that NA inhibition (NAI) antibody responses increase in a dose-dependent manner following a 2-dose priming series with AS03-adjuvanted influenza A(H7N9) inactivated vaccine (A(H7N9) IIV). NAI antibody responses also increase with interval extension of the 2-dose priming series or following a 5-year delayed boost with a heterologous adjuvanted A(H7N9) IIV. Neither concomitant seasonal influenza vaccination given simultaneously or sequentially, nor use of heterologous A(H7N9) IIVs in the 2-dose priming series had an appreciable effect on NAI antibody responses. Anti-HA stalk antibody responses were minimal and not durable. CONCLUSIONS: We provide evidence for strategies to improve anti-neuraminidase responses which can be further standardized for pandemic preparedness. CLINICAL TRIAL REGISTRY NUMBERS: NCT03312231, NCT03318315, NCT03589807, NCT03738241.

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.

BACKGROUND: In June 2021, the Advisory Committee on Immunization Practices (ACIP) recommended use of either 20-valent pneumococcal conjugate vaccine (PCV20) alone or 15-valent pneumococcal conjugate vaccine (PCV15) in series with 23-valent pneumococcal polysaccharide vaccine (PPSV23) for all PCV-unvaccinated adults aged ≥65 years (age-based) and for adults aged 19-64 years with conditions that increase the risk for pneumococcal disease (risk-based). This recommendation replaced a previous recommendation for PPSV23 with or without 13-valent pneumococcal conjugate vaccine (PCV13) for these groups. OBJECTIVE: We conducted a cost-effectiveness analysis of age-based and risk-based use of either PCV15 in series with PPSV23 or PCV20 alone when compared to previous recommendations. METHODS: We utilized probabilistic cohort models of all 65-year-olds (age-based) and 19-year-olds (risk-based through age 64 years and age-based at age 65 years). A spreadsheet-based Monte Carlo simulation software was used to estimate immunization costs, medical costs, non-medical costs, and overall disease burden under different vaccine strategies. The model tracked inpatient invasive pneumococcal disease (IPD) and non-bacteremic pneumonia (NBP) in inpatient and outpatient settings. One-way sensitivity analyses incorporated indirect effects of prospective pediatric vaccination with PCV15 and PCV20 on adult IPD and NBP incidence. Costs were reported in 2021 US dollars. All future costs and outcomes were discounted at 3 % per year. RESULTS: Age-based use of either PCV20 alone or PCV15 in series with PPSV23 at age 65 years were both shown to be cost-saving (improved health outcomes and saved costs). Combined cost-effectiveness of risk-based (19-64 years) plus age-based (65 years) (risk-and-age-based) use of PCV20 alone was cost-saving, whereas use of PCV15 in series with PPSV23 increased quality-adjusted life years (QALYs) but cost $412,111 (95 % CI: 270,295, 694,869) per QALY gained. CONCLUSION: In U.S. adults, replacing the previous recommendations with PCV20 alone or PCV15 in series with PPSV23 improved health outcomes. Except for risk-and-age-based use of PCV15 in series with PPSV23 that resulted in increased cost per QALY gained, the interventions also reduced costs.

Rotavirus is a leading cause of severe diarrheal disease in infants and young children worldwide. Vaccination offers the best protection against this disease, and two rotavirus vaccines were developed in India and included in its routine immunization program. The Government of India's decision to adopt this intervention was supported by a solid base of evidence from clinical trials, as well as substantial research regarding rotavirus disease burden and the potential health and economic value of immunization. Following program implementation, multiple studies were initiated, including three evaluations of effectiveness and several investigations regarding intussusception. These additional data regarding vaccine impact, safety, and delivery from post-introduction evaluations in conditions of real-world use will further strengthen and sustain the immunization program. This manuscript evaluates the status of existing and forthcoming evidence regarding rotavirus vaccination in India through a literature review and consultation with relevant stakeholders. Studies evaluating vaccine impact, effectiveness, safety, health economics, and acceptability, as well as operational and programmatic research, were included in the review. Overall, we found that the evidence base did not contain any major gaps. Nevertheless, additional smaller-scale research studies would be valuable in providing a more complete picture of rotavirus vaccine performance and benefit. Documentation of India's experience with rotavirus vaccines may provide lessons learned for other countries in the Asia region, where rotavirus disease burden remains high, yet vaccine adoption has been slow, as well as for countries worldwide that may be considering implementation of the Indian-made rotavirus vaccines.

OBJECTIVE: To evaluate human papillomavirus (HPV) vaccination coverage among adolescents in the U.S. using birth cohort analysis. METHODS: We conducted a birth cohort analysis among adolescents born during 1999-2009 using National Immunization Survey-Teen (NIS-Teen), a random-digit dialed household telephone survey that also includes vaccination data from providers. We analyzed 131,553 records from 2016 to 2022 NIS-Teen data to determine: trends in coverage with ≥1 HPV vaccine dose before age 13 years and cumulative coverage from age 13-17 years; sociodemographic factors associated with HPV vaccination before age 13 years; missed HPV vaccination opportunities and the potential achievable coverage if opportunities were not missed; and trends in completion of HPV vaccination series. Regression analysis and Kaplan-Meier method provided the average percentage increase in coverage, and cumulative coverage from age 13-17 years stratified by birth cohorts, respectively. RESULTS: HPV vaccination initiation before age 13 years increased from 27.0 % among adolescents born in 1999 to 69.8 % among those born in 2009. Overall, cumulative percent with ≥1 HPV vaccine dose increased from 51.3 % before age 13 years to 74.9 % through age 17 years. Having a preventive visit at ages 11-12 years and being insured were associated with higher ≥1 HPV vaccine dose coverage. Among the 38,568 (29.3 %) adolescents unvaccinated for HPV, 31,513 (82.5 %) missed ≥1 HPV vaccination opportunity. The potential achievable coverage if opportunities were not missed was 94.8 %. Completion of HPV vaccination series before age 13 years increased from 10.3 % among adolescents born in 1999 to 42.2 % among those born in 2009. CONCLUSIONS: Coverage with ≥1 HPV vaccine dose increased by birth cohort among adolescents born 1999-2009 but remained suboptimal, especially among uninsured adolescents. Missed opportunities may be reduced by effective HPV vaccination implementation and uptake strategies and by administering all recommended vaccines during the same visit.

INTRODUCTION: The Inflation Reduction Act (IRA) eliminated cost sharing for Medicare Part D-covered vaccines but did not address the cost burden faced by Medicare beneficiaries who did not have prescription drug coverage. This study aimed to determine the characteristics of beneficiaries without prescription drug coverage and to assess the association between the receipt of a herpes zoster vaccine and prescription drug coverage status. METHODS: We used the 2019-2023 National Health Interview Survey and included Medicare beneficiaries aged 65 years and older who enrolled in both Parts A and B or a Medicare Advantage plan. Descriptive statistics were used to examine beneficiaries' characteristics. Logistic regressions were used to examine the associations between the receipt of a herpes zoster vaccine and Medicare prescription drug coverage. RESULTS: The study included 33,578 beneficiaries and 93.5 % of beneficiaries had prescription drug coverage. The prevalence of lacking prescription drug coverage was higher among beneficiaries who did not have a college degree, had family income below the poverty level, had no flu shot and well visit within the past year, and had no usual place for care. The probability of receiving a herpes zoster vaccine was higher among beneficiaries with prescription drug coverage than those without prescription coverage (45.2 % versus 25.3 %). CONCLUSIONS: Herpes zoster vaccination disparities between beneficiaries with and without prescription drug coverage existed before the IRA. Because the IRA only addresses the cost barrier facing by beneficiaries with prescription drug coverage, vaccination disparities was greater after the IRA implementation.

BACKGROUND: In test-negative studies of vaccine effectiveness (VE), including patients with co-circulating, vaccine-preventable, respiratory pathogens in the control group for the pathogen of interest can introduce a downward bias on VE estimates. METHODS: A multicenter sentinel surveillance network in the US prospectively enrolled adults hospitalized with acute respiratory illness from September 1, 2022-March 31, 2023. We evaluated bias in estimates of VE against influenza-associated and COVID-19-associated hospitalization based on: inclusion vs exclusion of patients with a co-circulating virus among VE controls; observance of VE against the co-circulating virus (rather than the virus of interest), unadjusted and adjusted for vaccination against the virus of interest; and observance of influenza or COVID-19 against a sham outcome of respiratory syncytial virus (RSV). RESULTS: Overall VE against influenza-associated hospitalizations was 6 percentage points lower when patients with COVID-19 were included in the control group, and overall VE against COVID-19-associated hospitalizations was 2 percentage points lower when patients with influenza were included in the control group. Analyses of VE against the co-circulating virus and against the sham outcome of RSV showed that downward bias was largely attributable the correlation of vaccination status across pathogens, but also potentially attributable to other sources of residual confounding in VE models. CONCLUSION: Excluding cases of confounding respiratory pathogens from the control group in VE analysis for a pathogen of interest can reduce downward bias. This real-world analysis demonstrates that such exclusion is a helpful bias mitigation strategy, especially for measuring influenza VE, which included a high proportion of COVID-19 cases among controls.

Lassa fever is a serious epidemic viral disease in West Africa affecting an estimated 2 million people annually with about 5000-10,000 deaths, although supporting data is sparse. Lassa fever significantly affects neonates, children, and pregnant women, however, comprehensive data on its impact in these populations are lacking. We reviewed the available literature on Lassa fever to assess its prevalence and impact in these populations and implications for vaccine development. Clinical features in children were similar to those observed in adults, with complications such as bleeding. Altered mental status, anasarca (swollen baby syndrome), bleeding, and poor urine output were risk factors for death. The case fatality rate (CFR) in 16 paediatric studies ranged from 6 % to 63 % and was 66.7 % and 75.0 % in two neonatal studies. In a systematic review of studies on pregnant women the CFR was 33.73 %. The adverse foetal outcomes included miscarriage, stillbirth, and intrauterine death associated with maternal death. Since Lassa fever significantly affects neonates, children, and pregnant women, developing a safe and effective, single-dose vaccine for these high-risk populations is vital. Currently, there are four clinical trials assessing Lassa virus vaccines. Only one of these trials is enrolling children aged ≥18 months, and exclude pregnant and breast-feeding women. It is essential that pregnant and breast-feeding women and young children are included in clinical trials that incorporate robust safety surveillance and risk mitigation measures. In our review, potential approaches to address the specific gaps in the areas of diagnosis, management, and prevention of Lassa fever in these specific populations, such as disease surveillance systems and vaccine development, were identified. A comprehensive strategy with investment focused on addressing specific knowledge gaps will be essential in protecting the health of these specific populations in Lassa virus endemic regions.

BACKGROUND: The COVID-19 pandemic raised unprecedented challenges to vaccinating children. This multi-center study aimed to compare on-time vaccination of children before and during the COVID-19 pandemic and identify key factors associated with on-time vaccination. METHODS: This study was conducted among children aged 0-6 years enrolled in the New Vaccine Surveillance Network at seven geographically diverse U.S. academic medical centers. Children with acute respiratory illness or acute gastroenteritis were enrolled from emergency department and inpatient settings; healthy control subjects were enrolled from primary care practices. Vaccination data were collected and verified from patient medical records, immunization information systems, and/or provider documentation. On-time vaccination according to Advisory Committee on Immunization Practices recommendations was compared between pre-pandemic (December 2018-February 2020) and pandemic (March 2020-August 2021) periods using bivariate and multivariable analyses, adjusting for key demographic, clinical, and study characteristics. RESULTS: A total of 24,713 children were included in the analytic sample (non-Hispanic 73.4 %; White 51.0 %; publicly insured 69.0 %). On-time vaccination declined between the pre-pandemic (67.3 %) and pandemic (65.4 %) periods (Adjusted Odds Ratio 0.89, 95 % CI 0.84-0.95). The largest declines were observed among children who were < 12 months, male, Black, publicly insured, or whose mothers had a high school-equivalent education or less. The pandemic impact also varied by vaccine type and study site. CONCLUSIONS: This multi-center study revealed a relatively modest overall reduction in on-time vaccination, which may reflect multilevel efforts to address pandemic-associated challenges. However, some patient subgroups and sites experienced greater reductions in on-time vaccination, highlighting the importance of tailoring interventions to increase equitable vaccine delivery, access, and acceptance across populations and communities.