Interim 2025/26 influenza vaccine effectiveness estimates with immuno-epidemiological considerations for A(H3N2) subclade K protection, Canada, January 2026

In interim 2025/26 analyses, the Canadian Sentinel Practitioner Surveillance Network estimates influenza vaccine reduced the risk of medically-attended acute respiratory illness due to predominant influenza A(H3N2) viruses, including antigenically distinct subclade K, by about 40% relative to unvaccinated individuals. Vaccine effectiveness was about 30% against A(H1N1)pdm09, with insufficient case numbers for interim influenza B estimation. Meaningful protection against subclade K, despite substantial vaccine mismatch, is interpreted in the context of immuno-epidemiological considerations, including potential viral glycosylation, imprinting, and pre-immunity effects.

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Publication Details

Journal
Eurosurveillance
Published
2026-02-05
DOI
https://doi.org/10.2807/1560-7917.es.2026.31.5.2600068
Citations
10
Primary Topic
Influenza Virus Research Studies
Type
article
Field-Weighted Citation Impact
315.22
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article

Interim 2025/26 influenza vaccine effectiveness estimates with immuno-epidemiological considerations for A(H3N2) subclade K protection, Canada, January 2026

Charlene Ranadheera, Richard Mather, Samantha E Kaweski, Isabelle Meunier et al.
10 citations
Eurosurveillance
Influenza Virus Research Studies
315.22
article

Interim 2025/26 influenza vaccine effectiveness estimates with immuno-epidemiological considerations for A(H3N2) subclade K protection, Canada, January 2026

Charlene Ranadheera, Richard Mather, Samantha E Kaweski, Isabelle Meunier, Agatha N. Jassem, Romy Olsha, Suzana Sabaiduc, Nathan J. Zelyas, Christine Lacroix, Maan Hasso, Ruimin Gao, Katie Dover, Lila Naouelle Salhi, Sara Carazo, Lea Separovic, Yuping Zhan, Danuta M Skowronski, Nathalie Bastien
article en
10 citations

Abstract

In interim 2025/26 analyses, the Canadian Sentinel Practitioner Surveillance Network estimates influenza vaccine reduced the risk of medically-attended acute respiratory illness due to predominant influenza A(H3N2) viruses, including antigenically distinct subclade K, by about 40% relative to unvaccinated individuals. Vaccine effectiveness was about 30% against A(H1N1)pdm09, with insufficient case numbers for interim influenza B estimation. Meaningful protection against subclade K, despite substantial vaccine mismatch, is interpreted in the context of immuno-epidemiological considerations, including potential viral glycosylation, imprinting, and pre-immunity effects.

EurosurveillanceVol. 31(5)
University of British Columbia (CA), University of Calgary (CA), Public Health Agency of Canada (CA), Queen's University (CA), Alberta Hospital Edmonton (CA), BC Centre for Disease Control (CA), Institut National de Santé Publique du Québec (CA), Public Health Ontario (CA)
Good health and well-being
Openalex Percentile: Top 0%
Influenza Virus Research Studies
315.22
DOIOpen Access PDFOpenAlex
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