Influenza vaccine effectiveness from nine studies during drifted A(H3N2) subclade K predominance, Europe, September 2025 to January 2026

Eurosurveillance 2026 Open access

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Authors: Héloïse Lucaccioni, Diogo F.P. Marques, Freja Kirsebom, Hanne‐Dorthe Emborg, Mark Hamilton, Heather Whitaker, Amanda Bolt Botnen, Magda Bucholc, Francisco Pozo, Nick Andrews, Ramona Trebbien, Safraj Shahul Hameed
+9 more Karina Lauenborg Møller, Mark G. O’Doherty, Jamie Lopez-Bernal, Kirsty Morrison, Simon Cottrell, Suzanne Wilton, Angela MC Rose, Esther Kissling, the European IVE group
DOI: 10.2807/1560-7917.es.2026.31.7.2600109
Cited by: 12
References: 14

Abstract

The European 2025/26 influenza season is dominated by the influenza A(H3N2) virus, with most sequenced viruses belonging to subclade K, genetically drifted from the vaccine virus, raising concerns around vaccine effectiveness (VE). Despite this, VE estimates from nine European studies (19 countries) indicate all-age influenza A VE of 25-45% for outpatient and hospital settings combined, similar to other seasons, with highest estimates among children (47-72%). Vaccination should be encouraged and complemented by other infection prevention and control measures.

Fields of Study & Subjects

Influenza Virus Research Studies Respiratory viral infections research Pneumonia and Respiratory Infections

Publication details

Journal / source
Eurosurveillance
Publisher
European Centre for Disease Control and Prevention (ECDC)
Volume
31
Issue
7
Publication date
19 February 2026
Language
EN