CDC
CDC reports lower 2025–26 influenza vaccine effectiveness
A CDC analysis of interim vaccine effectiveness (VE) from three U.S. respiratory virus networks during the 2025–26 influenza season found that influenza vaccination reduced the risk of both outpatient visits and hospitalizations across all age groups, although protection was lower than in some recent seasons. Among children and adolescents, VE ranged from 38%–41% against influenza‑associated outpatient visits and 41% against hospitalization; among adults, VE was 22%–34% against outpatient visits and 30% against hospitalization.
Effectiveness varied by subtype: protection against influenza A(H3N2) ranged from 35%–42% in younger patients, while influenza B VE ranged from 45%–71% in children and 63% in adults. According to CDC, most circulating influenza A viruses were A(H3N2) subclade K, which differed antigenically from the season’s vaccine strain—a likely contributor to the modest performance observed.
CDC noted that, even in past seasons with reduced overall VE, influenza vaccines have provided meaningful benefit. For example, during the 2022–23 season, when VE was just 30%, influenza vaccination was estimated to prevent 71,000 hospitalizations and 4,300 deaths. With influenza still circulating, vaccination of eligible persons who haven't yet received a 2025–26 influenza vaccine could reduce influenza-associated morbidity and mortality.
Clinical takeaway: Continue to recommend influenza vaccination for all eligible patients aged 6 months and older, and use antivirals promptly for patients who are hospitalized, severely ill, or at high risk for complications.
Source:
Maloney P, Reeves EL, Wielgosz K, et al. (2026, March 12). Interim Estimates of 2025–26 Seasonal Influenza Vaccine Effectiveness — United States, September 2025–February 2026. MMWR. http://dx.doi.org/10.15585/mmwr.mm7509a2