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

Heloise Lucaccioni; Diogo Fp Marques; Freja Kirsebom; Hanne Dorthe Emborg; Mark Hamilton; Heather Whitaker; Amanda Bolt Botnen; Magda Bucholc; Francisco Pozo; Nick Andrews; Ramona Trebbien; Safraj Shahul Hameed; Karina Lauenborg Møller; Mark G. O’Doherty; Jamie Lopez-Bernal; Kirsty Morrison; Simon Cottrell; Suzanne Wilton; Angela Mc Rose; Esther Kissling

doi:10.2807/1560-7917.ES.2026.31.7.2600109

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

Heloise Lucaccioni
, Diogo Fp Marques
, Freja Kirsebom
, Hanne Dorthe Emborg
, Mark Hamilton
, Heather Whitaker
, Amanda Bolt Botnen
, Magda Bucholc
, Francisco Pozo
, Nick Andrews
, Ramona Trebbien
, Safraj Shahul Hameed
, Karina Lauenborg Møller
, Mark G. O’Doherty
, Jamie Lopez-Bernal
, Kirsty Morrison
, Simon Cottrell
, Suzanne Wilton
, Angela Mc Rose
, Esther Kissling

Research output: Contribution to journal › Article › peer-review

12 Citations (Scopus)

7 Downloads (Pure)

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.

Original language	English
Article number	2600109
Pages (from-to)	1-13
Number of pages	13
Journal	Eurosurveillance
Volume	31
Issue number	7
Early online date	19 Feb 2026
DOIs	https://doi.org/10.2807/1560-7917.ES.2026.31.7.2600109
Publication status	Published (in print/issue) - 19 Feb 2026

Bibliographical note

Publisher Copyright:
© 2026, European Centre for Disease Prevention and Control (ECDC). All rights reserved.

Data Availability Statement

Data are available from the corresponding author on request. The 1,763 sequences generated in connection with this analysis have been submitted to GISAID.

Funding

The EU-H study and EU-PC received funding from the European Centre for Disease Prevention and Control under framework contracts ECDC/2021/016 and ECDC/2021/019, respectively. The Belgian SARI surveillance is funded by the Belgian Federal Public Service ‘Health, Food Chain Safety, and Environment’ and the European Union (BE-SURVID project).

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

SDG 3 Good Health and Well-being

Keywords

Humans
Influenza A Virus, H3N2 Subtype/genetics
Influenza, Human/prevention & control
Influenza Vaccines/immunology
Europe/epidemiology
Vaccine Efficacy
Seasons
Vaccination/statistics & numerical data
Child
Child, Preschool

Access to Document

10.2807/1560-7917.ES.2026.31.7.2600109Licence: CC BY

eurosurv-31-7-1.cleanedFinal published version, 2 MBLicence: CC BY

Cite this

Lucaccioni, H., Marques, D. F., Kirsebom, F., Emborg, H. D., Hamilton, M., Whitaker, H., Botnen, A. B., Bucholc, M., Pozo, F., Andrews, N., Trebbien, R., Hameed, S. S., Møller, K. L., O’Doherty, M. G., Lopez-Bernal, J., Morrison, K., Cottrell, S., Wilton, S., Rose, A. M. (2026). Influenza vaccine effectiveness from nine studies during drifted A(H3N2) subclade K predominance, Europe, September 2025 to January 2026. Eurosurveillance, 31(7), 1-13. Article 2600109. https://doi.org/10.2807/1560-7917.ES.2026.31.7.2600109

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

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.",

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author = "Heloise Lucaccioni and Marques, \{Diogo Fp\} and Freja Kirsebom and Emborg, \{Hanne Dorthe\} and Mark Hamilton and Heather Whitaker and Botnen, \{Amanda Bolt\} and Magda Bucholc and Francisco Pozo and Nick Andrews and Ramona Trebbien and Hameed, \{Safraj Shahul\} and M{\o}ller, \{Karina Lauenborg\} and O{\textquoteright}Doherty, \{Mark G.\} and Jamie Lopez-Bernal and Kirsty Morrison and Simon Cottrell and Suzanne Wilton and Rose, \{Angela Mc\} and Esther Kissling and Bradley, \{Declan T.\} and Siobhan Murphy and Orla Crossan and Emma Dickson and Katja Hoschler and Beatrix Kele and Ross McQueenie and Kimberly Marsh and Jana Zitha and Panoraia Kalapotharakou and Simon Delusignan and Elizabeth Button and Parsy, \{Marie Pierre\} and M{\'e}lanie Delvallee and Pierre Struyven and Arne Witdouck and \{De Geyter\}, Deborah and \{Van Honacker\}, Eveline and Lucie Seyler and Siel Daelemans and Nicolas Dauby and Arthur Eggerickx and Catherine Quoidbach and Martin Vandeputte and \{Van Den Wijngaert\}, Sigi and David Tuerlinckx and Inge Engelrelst and Marijke Reynders and Koen Magerman and Marieke Bleyen",

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Lucaccioni, H, Marques, DF, Kirsebom, F, Emborg, HD, Hamilton, M, Whitaker, H, Botnen, AB, Bucholc, M, Pozo, F, Andrews, N, Trebbien, R, Hameed, SS, Møller, KL, O’Doherty, MG, Lopez-Bernal, J, Morrison, K, Cottrell, S, Wilton, S, Rose, AM, Kissling, E 2026, 'Influenza vaccine effectiveness from nine studies during drifted A(H3N2) subclade K predominance, Europe, September 2025 to January 2026', Eurosurveillance, vol. 31, no. 7, 2600109, pp. 1-13. https://doi.org/10.2807/1560-7917.ES.2026.31.7.2600109

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AU - Emborg, Hanne Dorthe

AU - Hamilton, Mark

AU - Whitaker, Heather

AU - Botnen, Amanda Bolt

AU - Bucholc, Magda

AU - Pozo, Francisco

AU - Andrews, Nick

AU - Trebbien, Ramona

AU - Hameed, Safraj Shahul

AU - Møller, Karina Lauenborg

AU - O’Doherty, Mark G.

AU - Lopez-Bernal, Jamie

AU - Morrison, Kirsty

AU - Cottrell, Simon

AU - Wilton, Suzanne

AU - Rose, Angela Mc

AU - Kissling, Esther

AU - Bradley, Declan T.

AU - Murphy, Siobhan

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AU - Dickson, Emma

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AU - Kalapotharakou, Panoraia

AU - Delusignan, Simon

AU - Button, Elizabeth

AU - Parsy, Marie Pierre

AU - Delvallee, Mélanie

AU - Struyven, Pierre

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AU - Van Honacker, Eveline

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AU - Quoidbach, Catherine

AU - Vandeputte, Martin

AU - Van Den Wijngaert, Sigi

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AU - Bleyen, Marieke

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AB - 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.

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KW - Influenza A Virus, H3N2 Subtype/genetics

KW - Influenza, Human/prevention & control

KW - Influenza Vaccines/immunology

KW - Europe/epidemiology

KW - Vaccine Efficacy

KW - Seasons

KW - Vaccination/statistics & numerical data

KW - Child

KW - Child, Preschool

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ER -

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

Abstract

Bibliographical note

Data Availability Statement

Funding

UN SDGs

Keywords

Access to Document

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