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

Eurosurveillance 2026 Open access

Read full text
Authors: Lea Separovic, Suzana Sabaiduc, Yuping Zhan, Samantha E Kaweski, Romy Olsha, Maan Hasso, Richard Mather, Sara Carazo, Christine Lacroix, Isabelle Meunier, Lila Naouelle Salhi, James A. Dickinson
+7 more Nathan Zelyas, Agatha N. Jassem, Katie Dover, Charlene Ranadheera, Ruimin Gao, Nathalie Bastien, Danuta M Skowronski
DOI: 10.2807/1560-7917.es.2026.31.5.2600068
Cited by: 22
References: 22

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.

Fields of Study & Subjects

Influenza Virus Research Studies Respiratory viral infections research Immune responses and vaccinations

Publication details

Journal / source
Eurosurveillance
Publisher
European Centre for Disease Control and Prevention (ECDC)
Volume
31
Issue
5
Publication date
5 February 2026
Language
EN