Early influenza virus characterisation and vaccine effectiveness in England in autumn 2025, a period dominated by influenza A(H3N2) subclade K

Freja C.M. Kirsebom; Catherine Thompson; Tiina Talts; Beatrix Kele; Heather J. Whitaker; Nick Andrews; Nurin Abdul Aziz; Christopher Rawlinson; Rebecca E. Green; Catherine Quinot; Nicholas Gardner; Elizabeth Waller; Alex Allen; Conall H. Watson; Suzanna L.R. McDonald; Maria Zambon; Richard Pebody; Mary Ramsay; Katja Hoschler; Anika Singanayagam; Jamie Lopez Bernal

doi:10.2807/1560-7917.ES.2025.30.46.2500854

Early influenza virus characterisation and vaccine effectiveness in England in autumn 2025, a period dominated by influenza A(H3N2) subclade K

Freja C.M. Kirsebom^*
, Catherine Thompson
, Tiina Talts
, Beatrix Kele
, Heather J. Whitaker
, Nick Andrews
, Nurin Abdul Aziz
, Christopher Rawlinson
, Rebecca E. Green
, Catherine Quinot
, Nicholas Gardner
, Elizabeth Waller
, Alex Allen
, Conall H. Watson
, Suzanna L.R. McDonald
, Maria Zambon
, Richard Pebody
, Mary Ramsay
, Katja Hoschler
, Anika Singanayagam

Jamie Lopez Bernal

^*Corresponding author for this work

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

1 Citation (Scopus)

Abstract

Influenza A(H3N2) subclade K (J.2.4.1) has dominated the 2025/26 season start in England. Post-infection ferret antisera raised against northern hemisphere 2025/26 vaccine strains showed reduced reactivity to subclade K viruses in England, aligning with World Health Organization reports. Nevertheless, early post-vaccination, vaccine effectiveness against influ enza-related emergency department attendances and hospital admissions remained within typical ranges, at 72–75% in children and adolescents (< 18 years) and 32–39% in adults. Hence, vaccination remains effective against clinical disease caused by influenza A(H3N2) viruses.

Original language	English
Article number	2500854
Journal	Eurosurveillance
Volume	30
Issue number	46
DOIs	https://doi.org/10.2807/1560-7917.ES.2025.30.46.2500854
Publication status	Published - 20 Nov 2025

Bibliographical note

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© 2025, European Centre for Disease Prevention and Control (ECDC). All rights reserved.

UN SDGs

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

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10.2807/1560-7917.ES.2025.30.46.2500854

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Kirsebom, F. C. M., Thompson, C., Talts, T., Kele, B., Whitaker, H. J., Andrews, N., Aziz, N. A., Rawlinson, C., Green, R. E., Quinot, C., Gardner, N., Waller, E., Allen, A., Watson, C. H., McDonald, S. L. R., Zambon, M., Pebody, R., Ramsay, M., Hoschler, K., ... Bernal, J. L. (2025). Early influenza virus characterisation and vaccine effectiveness in England in autumn 2025, a period dominated by influenza A(H3N2) subclade K. Eurosurveillance, 30(46), Article 2500854. https://doi.org/10.2807/1560-7917.ES.2025.30.46.2500854

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title = "Early influenza virus characterisation and vaccine effectiveness in England in autumn 2025, a period dominated by influenza A(H3N2) subclade K",

abstract = "Influenza A(H3N2) subclade K (J.2.4.1) has dominated the 2025/26 season start in England. Post-infection ferret antisera raised against northern hemisphere 2025/26 vaccine strains showed reduced reactivity to subclade K viruses in England, aligning with World Health Organization reports. Nevertheless, early post-vaccination, vaccine effectiveness against influ enza-related emergency department attendances and hospital admissions remained within typical ranges, at 72–75\% in children and adolescents (< 18 years) and 32–39\% in adults. Hence, vaccination remains effective against clinical disease caused by influenza A(H3N2) viruses.",

author = "Kirsebom, \{Freja C.M.\} and Catherine Thompson and Tiina Talts and Beatrix Kele and Whitaker, \{Heather J.\} and Nick Andrews and Aziz, \{Nurin Abdul\} and Christopher Rawlinson and Green, \{Rebecca E.\} and Catherine Quinot and Nicholas Gardner and Elizabeth Waller and Alex Allen and Watson, \{Conall H.\} and McDonald, \{Suzanna L.R.\} and Maria Zambon and Richard Pebody and Mary Ramsay and Katja Hoschler and Anika Singanayagam and Bernal, \{Jamie Lopez\}",

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doi = "10.2807/1560-7917.ES.2025.30.46.2500854",

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Kirsebom, FCM, Thompson, C, Talts, T, Kele, B, Whitaker, HJ , Andrews, N, Aziz, NA, Rawlinson, C, Green, RE, Quinot, C, Gardner, N, Waller, E, Allen, A, Watson, CH, McDonald, SLR, Zambon, M , Pebody, R , Ramsay, M , Hoschler, K, Singanayagam, A & Bernal, JL 2025, 'Early influenza virus characterisation and vaccine effectiveness in England in autumn 2025, a period dominated by influenza A(H3N2) subclade K', Eurosurveillance, vol. 30, no. 46, 2500854. https://doi.org/10.2807/1560-7917.ES.2025.30.46.2500854

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T1 - Early influenza virus characterisation and vaccine effectiveness in England in autumn 2025, a period dominated by influenza A(H3N2) subclade K

AU - Kirsebom, Freja C.M.

AU - Thompson, Catherine

AU - Talts, Tiina

AU - Kele, Beatrix

AU - Whitaker, Heather J.

AU - Andrews, Nick

AU - Aziz, Nurin Abdul

AU - Rawlinson, Christopher

AU - Green, Rebecca E.

AU - Quinot, Catherine

AU - Gardner, Nicholas

AU - Waller, Elizabeth

AU - Allen, Alex

AU - Watson, Conall H.

AU - McDonald, Suzanna L.R.

AU - Zambon, Maria

AU - Pebody, Richard

AU - Ramsay, Mary

AU - Hoschler, Katja

AU - Singanayagam, Anika

AU - Bernal, Jamie Lopez

PY - 2025/11/20

Y1 - 2025/11/20

N2 - Influenza A(H3N2) subclade K (J.2.4.1) has dominated the 2025/26 season start in England. Post-infection ferret antisera raised against northern hemisphere 2025/26 vaccine strains showed reduced reactivity to subclade K viruses in England, aligning with World Health Organization reports. Nevertheless, early post-vaccination, vaccine effectiveness against influ enza-related emergency department attendances and hospital admissions remained within typical ranges, at 72–75% in children and adolescents (< 18 years) and 32–39% in adults. Hence, vaccination remains effective against clinical disease caused by influenza A(H3N2) viruses.

AB - Influenza A(H3N2) subclade K (J.2.4.1) has dominated the 2025/26 season start in England. Post-infection ferret antisera raised against northern hemisphere 2025/26 vaccine strains showed reduced reactivity to subclade K viruses in England, aligning with World Health Organization reports. Nevertheless, early post-vaccination, vaccine effectiveness against influ enza-related emergency department attendances and hospital admissions remained within typical ranges, at 72–75% in children and adolescents (< 18 years) and 32–39% in adults. Hence, vaccination remains effective against clinical disease caused by influenza A(H3N2) viruses.

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AN - SCOPUS:105022522646

SN - 1025-496X

VL - 30

JO - Eurosurveillance

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IS - 46

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ER -

Early influenza virus characterisation and vaccine effectiveness in England in autumn 2025, a period dominated by influenza A(H3N2) subclade K

Abstract

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