Flu Vaccine Cut Hospitalizations Despite Drifted H3N2 Strain

Interim CDC estimates found the 2025–2026 vaccine reduced outpatient influenza visits by up to 41% and hospitalizations by up to 41%.

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The 2025–2026 influenza vaccine reduced outpatient visits by 22% to 34% and hospitalizations by 30%, especially in pediatric patients.
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Pediatric patients showed the strongest protection, with hospitalization effectiveness reaching 41% and outpatient effectiveness ranging from 38% to 41%.
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Among adults, vaccine effectiveness against hospitalizations was estimated at 30%, with outpatient effectiveness ranging from 22% to 34%.
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Influenza A(H3N2) subclade K was found in 83% of characterized A(H3N2) viruses, differing antigenically from the vaccine strain.
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Despite antigenic drift, vaccination significantly reduced influenza-associated morbidity, with CDC recommending vaccination for all eligible individuals.

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