National Center for Immunization and Respiratory Diseases

Digital surveys and electronic health records (EHR) can be combined to provide comprehensive assessments of vaccine safety. Limited post-marketing safety data exists for two new RSV vaccines among older adults (Pfizer RSVPreF and GSK RSVPreF3+ASO1). We used digital survey data from adults ≥60years receiving RSV vaccines through Kaiser Permanente Southern California from November 8, 2023, to February 29, 2024. Enrolled participants received 14-day post-vaccination surveys soliciting local and systemic reactions. Survey results were combined with EHR data. Medical chart reviews were conducted among participants self-reporting receiving medical care for vaccine-related symptoms within 21days of vaccination. We recruited 14,482 participants aged ≥60years following RSV vaccination (GSK: 7873 [59%]; Pfizer: 5555 [41%]), including 1054 participants receiving COVID-19 vaccinations on the same day (GSK:618; Pfizer:436). Local and systemic reactions were reported more frequently following GSK vaccinations than Pfizer. The most frequently reported reactions were pain at injection site (56.5% and 14.4%, respectively), fatigue (35.5% and 21.8%), myalgia (26.2% and 13.0%), headache (21.5% and 12.8%) and fever (7.8% and 3.3%). Participants rarely reported seeking medical care (GSK: 158/7873;2.0%; Pfizer: 104/5555;1.9%). Of these, 229 had ≥1 EHR-documented medical encounter 0-21days post-vaccination, of which 102 (0.8%) were considered possibly related to vaccination (GSK:69; Pfizer:33; RSV+COVID-19:0). Via chart review, the most common diagnoses identified as possibly related to vaccination included respiratory symptoms, such ascough (n=20 and n=9, respectively) and congestion (n=13 and n=6). No severe events were deemed related to vaccination. Reported reactogenicity symptoms were higher among participants receiving COVID-19 vaccines on the same day compared to participants receiving RSV vaccines alone. The most common reactions after RSV vaccines were local pain, fatigue, myalgia, and headache. GSK vaccine recipients containing the AS01E adjuvant reported reactions more frequently than Pfizer vaccine recipients. Consistent with pre-licensure safety data, most symptoms were transient and did not require medical care.

Severe rhinovirus (RV)/enterovirus (EV) respiratory infections in pediatric patients increased in the US during 2022-2023. This study aimed to characterize RV/EV genetic diversity among hospitalized children in Wisconsin and describe demographic and clinical factors of patients by RV/EV type. During September 2022-April 2023, five Wisconsin pediatric hospitals submitted five RV/EV-positive specimens weekly to CDC. Viral typing was performed using partial viral protein (VP) 4/VP2 (RV) and VP1 (EV) sequencing. Wisconsin Department of Health Services abstracted demographic, comorbid condition, and hospitalization course information from patient medical records. Ninety-six patients were included in this investigation. RV-C (n = 40, 42%) and RV-A (n = 31, 32%) were the most frequently detected species, with 46 RV and 5 EV types identified. The median age was 2.5 (IQR: 0.7-5.5) years. Seventy-one (74%) children had at least one comorbid condition. Asthma was more common among children with RV-C infections (n = 12, 30%) compared with other RVs (n = 3, 9%) (p = 0.02). RV-A and RV-C were important contributors to severe pediatric respiratory infection in Wisconsin. Molecular typing showed virus divergence typically observed during season-long investigations. Year-round molecular characterization is needed to better understand the contribution of RV/EV types to severe pediatric respiratory illness.

Infection of backyard and poultry with low pathogenicity avian influenza LPAI A(H5N2) viruses has occurred in Mexico since 1994, and the first human infection caused by this influenza virus was detected in 2024. Since its emergence in the Americas, frequent reassortments between high pathogenicity avian influenza HPAI A(H5N1) and LPAI viruses has occurred. In September 2025, the Instituto Nacional de Enfermedades Respiratorias of Mexico City identified an unsubtypeable influenza A virus infection in a young adult patient later determined to be a reassortant HPAI (H5N2) virus with a clade 2.3.4.4b HA. We analyzed clinical and epidemiologic data from this patient. Respiratory samples were tested for influenza RT-qPCR assays. Genomic sequence and phylogenetics analyses were performed to provisionally assign a new genotype to the novel HPAI A(H5N2) reassortant virus. The patient presented with fever and tachypnea, later developed hemoptysis and thoracic pain, with oxygen saturation decreasing to 70%. CT scan showed bilateral ground-glass opacities consistent with diffuse alveolar hemorrhage and zones consistent with consolidation. Clinical improvement was observed and the patient was discharged. Through viral complete genome analysis, we identified an HPAI A(H5N2) virus with genes from both clade 2.3.4.4b A(H5N1) viruses similar to those detected in North America during 2022-2023 and genes from the LPAI A(H5N2) viruses detected in Mexico during 2024. This is the first ever laboratory-confirmed human infection caused by an HPAI A(H5N2) virus infection, suggesting a new genotype provisionally classified as B3.14. The relationship of the virus with the severity of illness remains unknown.

Abstract Background Long COVID has emerged as a major public-health concern in the United States, yet geographic variation in its prevalence remains poorly understood. This study examines how state-level differences in COVID-19 vaccination, SARS-CoV-2 incidence, COVID-19 hospitalization, and chronic disease burden relate to adult Long COVID prevalence in the United States. Methods We conducted an ecological analysis using data from the 2023 Behavioral Risk Factor Surveillance System (BRFSS), from which we estimated state-level prevalence of self-reported Long COVID among adults. These estimates were linked with publicly available data on SARS-CoV-2 incidence, COVID-19 hospitalizations, COVID-19 vaccine coverage, and a multimorbidity indicator (>= 3 chronic conditions e.g., diabetes, obesity, chronic kidney disease) associated with higher risk for severe SARS-CoV-2. Multivariable linear regression models were fitted to assess the contribution of each factor adjusted for age and sex distribution, incorporating Rubin’s rules to account for uncertainty in prevalence estimates. Results All examined factors—including SARS-CoV-2 incidence, hospitalization rates, and multimorbidity, vaccine coverage—varied by state. When modeled simultaneously and adjusting for age and sex distribution, only COVID-19 vaccine coverage and SARS-CoV-2 incidence were significantly associated with Long COVID prevalence. COVID-19 vaccine coverage showed a strong protective association, while SARS-CoV-2 incidence showed a modest positive association. Multimorbidity and hospitalization rates were not independently associated with adjustment. Conclusions State-level variation in Long COVID burden appears most strongly driven by COVID-19 vaccine coverage and SARS-CoV-2 incidence. Promoting COVID-19 vaccination remains essential to reduce long-term impacts from SARS-CoV-2 infections.

Objective: To understand the dynamics of vaccination conversations between obstetrician/gynecologists and pregnant women and the factors influencing vaccine acceptance and differences by patient race and ethnicity. Methods: In this qualitative study we used linguistic analysis to analyze vaccination conversations between 40 unique patients and 10 unique providers from the 2020 to 2021 influenza season. The results were stratified for non-Hispanic White (“White”) patients compared to non-Hispanic Black and Hispanic patients (“patients of color/POC”) to assess differences in the strength of provider vaccine recommendations, initiation of vaccination conversation, the patient reaction to vaccination prompts, and association of these factors with vaccination intent as the primary outcome. Results: The linguistic analysis demonstrated that 22 (55%) out of 40 patients intended to get vaccinated. More POC delayed or refused influenza vaccination (3/6) than White patients (2/10), while more White patients (5/5) than POC demonstrated intent to get the Tdap vaccine (6/10). While providers consistently explained the value of vaccination, greater emphasis was placed on communicating the benefits of Tdap compared with influenza vaccination to POC. Providers used fewer techniques indicative of strong vaccine recommendations when recommending influenza vaccination to POC compared with White patients. Conclusion: This hypothesis-generating study suggests some aspects of provider communication about prenatal vaccination may differ by patients’ race and ethnicity. Provider-based interventions to improve communication with pregnant women about prenatal vaccines may improve vaccine uptake and reduce racial and ethnic disparities.

Health workers (HWs) set an example for vaccine recipients, convey vaccine benefits and risks and interface with patients at increased risk for complications in pandemic settings. We explored HWs' acceptance of and recommendation for COVID-19 vaccine with and without previous receipt of seasonal influenza vaccine (SIV) in nine countries. In 2023-2024, cross-sectional surveys among HW were conducted in Bangladesh, Cote d'Ivoire, Ghana, Laos, Lebanon, Morocco, Philippines, Thailand and Tunisia. Country researchers used a standard protocol and questionnaire to assess beliefs, perceptions and acceptance around SIV and COVID-19 vaccine and likelihood of recommending these vaccines to patients. Pooled findings were stratified by the presence or absence of a national HW SIV recommendation. Generalised mixed effects models were used to characterise the relationship between receipt of SIV and COVID-19 vaccine acceptance and recommendation, adjusting for WHO region, sex and duration of employment. Our analysis included 12 296 HWs from nine countries representing four WHO regions: African, Eastern Mediterranean, Southeast Asian and Western Pacific. Five countries had a national HW SIV recommendation (61% of HWs surveyed) prior to COVID-19 vaccine introduction. More than 90% of HWs reported completing the COVID-19 vaccination series, whereas intention to continue receiving annual COVID-19 vaccine was lower (61%). HWs who received SIV in the last season compared with those who did not were more likely to have received one or more COVID-19 booster doses (adjusted OR (aOR) 2.63, 95% CI 2.27 to 3.04) and to have recommended COVID-19 vaccine to patients (aOR 1.53, 95% CI 1.29 to 1.82). Prior experience with SIV was associated with HW behaviour and recommendations regarding COVID-19 vaccination. Intention to continue receiving COVID-19 vaccines remains a challenge; ongoing training and education for vaccination staff could be beneficial. HWs play a critical role in the successful delivery of new and existing vaccines, particularly in a pandemic setting.

BackgroundLittle data are available describing the circulation of respiratory viruses in pre-kindergarten (preK)-12th grade schools. Performing viral surveillance testing in students and staff can be resource intensive and requires large scale participation. Air sampling for respiratory viruses in schools could be a proxy to human sampling. Our objective was to describe the overlap of respiratory viral detection in human and air specimens collected concurrently.Respiratory viruses detected from air samples and nasal swab specimens in elementary schools in Kansas City, MO from September 2024- March 2025.Figure 2.Concordance of respiratory virus detections from matched air and human specimens in elementary schools in Kansas City, MO from September 2024-March 2025.MethodsSchool KIDS is a prospective respiratory virus surveillance program for students and staff in a preK-12th grade public school district in Kansas City, MO. In 15 classrooms across 5 elementary schools (3 classrooms/school), human (anterior nares) specimens were collected monthly; air samples were collected on the same day every 2-4 weeks using AerosolSense samplers (ThermoFisher Scientific) operating at 200 L/minute for 8 school hours. All specimens were tested by PCR for adenovirus, human metapneumovirus, influenza, parainfluenza viruses 1-4, respiratory syncytial virus, rhinovirus/ enterovirus (RV/EV), seasonal coronaviruses (sCoV) OC43, NL63, HKU1, 229E, and SARS-CoV-2. Concordance—defined as detection of the same virus in both air and human samples from the same room and day—was assessed.ResultsFrom September 18, 2024-March 31, 2025, 160 air samples were collected concurrently with 561 human specimens, with a median of 3 [IQR 3,5] human specimens per air sample. Viruses were detected in 142/160 (89%) air samples, with a total of 348 viral detections. Of 160 air samples, 64 (40%) had the concurrent detection in at least one match human specimen. Of 561 human samples, 104 (18%) had the same virus as in matched air samples. Of the 561 human specimens, 144 (25%) had ≥1 virus detected with a total of 152 viral detections. RV/EV (128/160) and SARS-CoV-2 (61/160) were the most frequently detected viruses in air, while RV/EV (83/561) and sCoV OC43 (20/561) were the most frequently detected in human specimens (Fig 1). RV/EV (n=51) and sCoV OC43 (n=7) were the viruses most frequently identified from matched human and air samples (Fig 2).ConclusionAir sampling in schools may be useful to detect circulating viruses in schools. Further studies are needed to determine whether air sampling can be a proxy for human sampling.DisclosuresBrian R. Lee, PhD, MPH, Merck: Grant/Research Support Rangaraj Selvarangan, PhD, Altona: Grant/Research Support|Biomerieux: Advisor/Consultant|Biomerieux: Grant/Research Support|Biomerieux: Honoraria|Cepheid: Grant/Research Support|Hologic: Grant/Research Support|Hologic: Honoraria|Meridian: Grant/Research Support|Qiagen: Grant/Research Support

Rotavirus vaccine clinical trials and post-licensure evaluations found malnourished children may have lower protection against rotavirus diarrhea hospitalizations than well-nourished children. On a population level, rotavirus vaccines are less protective in high child mortality settings. We analyzed rotavirus vaccine effectiveness (VE) among malnourished and well-nourished children categorized using four anthropometric malnutrition indicators, birthweight, and reported malnutrition from medium to high child mortality countries in the Multi-National Subpopulations Study to Evaluate Rotavirus Vaccines (MNSSTER-V) dataset. We calculated child-level z-scores for weight-for-age, length-for-age, weight-for-length, and mid-upper arm circumference (MUAC), and the site-level proportion implausible z-scores. Sites with published VE estimates by nutritional status or those with <3% implausible values were included in the final analysis. Z-scores <-2 were considered moderate-to-severe malnutrition and <-3 were considered severe malnutrition. We calculated complete series rotavirus VE in each malnourished and well-nourished group using an unconditional adjusted logistic regression model, where VE = (1 - odds ratio of vaccination among cases and controls) × 100, where cases and controls were children who tested rotavirus positive and negative, respectively. Complete series VE was more protective among children without stunting (normal length-for-age) (59%; 95% confidence interval [CI]: 49-67) compared to children with moderate-to-severe stunting (42%; 95% CI: 19-58) and severe stunting (31%; 95%CI: -14 to 58). Adjusted VE point estimates were similar among malnourished and well-nourished children using the other anthropometric and birthweight indicators. Our findings clearly show that chronic malnutrition negatively impacted rotavirus VE. Efforts to address and prevent malnutrition generally may further reduce the burden of rotavirus morbidity and mortality.