Mariëtte Hooiveld
Publicatie
Datum
19-02-2026
Influenza vaccine effectiveness from nine studies during drifted A(H3N2) subclade K predominance, Europe, September 2025 to January 2026.
Lucaccione, H., Marques, D.F.P., Kirsebom, F., Emborg, H.D., Hamilton, M., Whitaker, H., Bolt Botnen, A., Bucholc, M., Pozo, F., Andrews, N., Trebbien, R., Hameed, S.S., Lauenborg Møller, K., O'Doherty, M.G., Lopez-Bernal, J., Morrison, K., Cottrell, S., Wilton, S., Rose, A.M.C., Kissling, E., Hooiveld. Influenza vaccine effectiveness from nine studies during drifted A(H3N2) subclade K predominance, Europe, September 2025 to January 2026. Eurosurveillance: 2026. 31(7), art. nr. 2600109.
Lees online
The World Health Organization (WHO) recommendations for the 2025/26 northern hemisphere influenza vaccination for influenza virus type A included an A/Victoria/4897/2022 (H1N1)pdm09-like and an A/Croatia/10136RV/2023 A(H3N2)-like virus for egg-based vaccines and an A/Wisconsin/67/2022 (H1N1)pdm09-like and an A/District of Columbia/27/2023 (H3N2)-like virus for cell-based vaccines [1]. Although the influenza A(H3N2) vaccine component differs from previous seasons, the vaccine recommendations for the influenza A(H1N1)pdm09 vaccine component have remained unchanged since the 2023/24 season [2,3].
The influenza season started early in some European countries, with influenza A viruses predominating between September 2025 and January 2026. Most subtyped viruses were influenza A(H3N2), among which subclade K was dominant [4]. This subclade is highly drifted from the influenza A(H3N2) virus included in the vaccine strain (subclade J.2), suggesting potential for immune escape [5,6]. However, early influenza vaccine effectiveness (VE) estimates in November and December 2025 indicated VE against influenza A(H3N2) of ≥ 50% in individuals aged younger than 65 years [7,8].
The influenza season started early in some European countries, with influenza A viruses predominating between September 2025 and January 2026. Most subtyped viruses were influenza A(H3N2), among which subclade K was dominant [4]. This subclade is highly drifted from the influenza A(H3N2) virus included in the vaccine strain (subclade J.2), suggesting potential for immune escape [5,6]. However, early influenza vaccine effectiveness (VE) estimates in November and December 2025 indicated VE against influenza A(H3N2) of ≥ 50% in individuals aged younger than 65 years [7,8].
The World Health Organization (WHO) recommendations for the 2025/26 northern hemisphere influenza vaccination for influenza virus type A included an A/Victoria/4897/2022 (H1N1)pdm09-like and an A/Croatia/10136RV/2023 A(H3N2)-like virus for egg-based vaccines and an A/Wisconsin/67/2022 (H1N1)pdm09-like and an A/District of Columbia/27/2023 (H3N2)-like virus for cell-based vaccines [1]. Although the influenza A(H3N2) vaccine component differs from previous seasons, the vaccine recommendations for the influenza A(H1N1)pdm09 vaccine component have remained unchanged since the 2023/24 season [2,3].
The influenza season started early in some European countries, with influenza A viruses predominating between September 2025 and January 2026. Most subtyped viruses were influenza A(H3N2), among which subclade K was dominant [4]. This subclade is highly drifted from the influenza A(H3N2) virus included in the vaccine strain (subclade J.2), suggesting potential for immune escape [5,6]. However, early influenza vaccine effectiveness (VE) estimates in November and December 2025 indicated VE against influenza A(H3N2) of ≥ 50% in individuals aged younger than 65 years [7,8].
The influenza season started early in some European countries, with influenza A viruses predominating between September 2025 and January 2026. Most subtyped viruses were influenza A(H3N2), among which subclade K was dominant [4]. This subclade is highly drifted from the influenza A(H3N2) virus included in the vaccine strain (subclade J.2), suggesting potential for immune escape [5,6]. However, early influenza vaccine effectiveness (VE) estimates in November and December 2025 indicated VE against influenza A(H3N2) of ≥ 50% in individuals aged younger than 65 years [7,8].
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