Influenza Activity and Estimated Vaccine Effectiveness During the 2025-2026 Influenza Season - Summary - MDSpire

Influenza Activity and Estimated Vaccine Effectiveness During the 2025-2026 Influenza Season

  • By

  • Eduardo Azziz-Baumgartner

  • Alicia Budd

  • Justin S. Lee

  • A. Danielle Iuliano

  • Sascha R. Ellington

  • Min Z. Levine

  • Xiao-yu Zheng

  • Larisa Gubareva

  • Katherine Adams

  • Jennifer DeCuir

  • Catherine H. Bozio

  • Carrie Reed

  • Marie K. Kirby

  • Benjamin Rambo-Martin

  • Jefferson M. Jones

  • Matthew Biggerstaff

  • Shikha Garg

  • Charles Todd Davis

  • Tom T. Shimabukuro

  • Erin Burns

  • Rebecca Kondor

  • Sonja J. Olsen

  • Vivien G. Dugan

  • VISION Coauthors

  • Stephanie A. Irving

  • Allison L. Naleway

  • Kristin Dascomb

  • Tamara Sheffield

  • Malini B. DeSilva

  • Sara Y. Tartof

  • Lina S. Sy

  • Nicola P. Klein

  • Ousseny Zerbo

  • Shaun J. Grannis

  • Brian E. Dixon

  • Melissa S. Stockwell

  • Ashley B. Stephens

  • Toan C. Ong

  • Michelle A. Barron

  • Sarah W. Ball

  • Zachary A. Weber

  • Emily L. Reeves

  • Caitlin S. Ray

  • June 17, 2026

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Objective:

To provide US virologic, immunologic, and epidemiologic findings regarding influenza A(H3N2) viruses and vaccine effectiveness during the 2025-2026 season.

Approach:
    Key Findings:
    • Ten mutations in the HA protein of influenza A(H3N2) viruses were identified, indicating potential vaccine escape.
    • The emergence of subclade K viruses led to a protracted epidemic in Australia and an early severe season in Japan.
    • Antigenic drift was observed in circulating A(H3N2) viruses compared to the vaccine reference virus.
    Interpretation:

    The findings indicate significant changes in circulating influenza A(H3N2) viruses that may affect vaccine efficacy.

    Limitations:
    • The study is based on data collected from specific regions and may not represent the entire US population.
    • Ethical considerations limited the scope of certain data collection methods.
    Conclusion:

    The study highlights the need for ongoing surveillance and assessment of influenza virus changes to inform vaccine development.

    Sources:

Original Source(s)

Influenza Activity and Estimated Vaccine Effectiveness During the 2025-2026 Influenza Season

  • by Eduardo Azziz-Baumgartner, Alicia Budd, Justin S. Lee, A. Danielle Iuliano, Sascha R. Ellington, Min Z. Levine, Xiao-yu Zheng, Larisa Gubareva, Katherine Adams, Jennifer DeCuir, Catherine H. Bozio, Carrie Reed, Marie K. Kirby, Benjamin Rambo-Martin, Jefferson M. Jones, Matthew Biggerstaff, Shikha Garg, Charles Todd Davis, Tom T. Shimabukuro, Erin Burns, Rebecca Kondor, Sonja J. Olsen, Vivien G. Dugan, VISION Coauthors, Stephanie A. Irving, Allison L. Naleway, Kristin Dascomb, Tamara Sheffield, Malini B. DeSilva, Sara Y. Tartof, Lina S. Sy, Nicola P. Klein, Ousseny Zerbo, Shaun J. Grannis, Brian E. Dixon, Melissa S. Stockwell, Ashley B. Stephens, Toan C. Ong, Michelle A. Barron, Sarah W. Ball, Zachary A. Weber, Emily L. Reeves, Caitlin S. Ray

  • June 17, 2026

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