Results 11 to 20 of about 8,158 (163)

Extended influenza seasons in Australia and New Zealand in 2025 due to the emergence of influenza A(H3N2) subclade K viruses [PDF]

Eurosurveillance
In Australia and New Zealand, late outbreaks of an A(H3N2) variant virus termed subclade K extended the 2025 influenza season. Subclade K viruses were genetically and antigenically distinct from the 2025 vaccine A(H3N2) strain A/Croatia/10136RV/2023 ...
Lauren Jelley, Tim Wood
exaly   +6 more sources

Seasonal vaccine-induced immunity shows preserved cross-reactivity to H3N2 subclade K in adultsResearch in context [PDF]

EBioMedicine
Summary: Background: Influenza A subclade K viruses caused high infection rates in the 2025/2026 Northern Hemisphere season, raising concerns about antigenic drift and reduced vaccine effectiveness.
Adria Wilson, Brian Lerman, Reima Ramsamooj, Jacob Mischka, Jordan Ehrenhaus, Ashley Aracena, Yusuf Figueroa, Keith Farrugia, Ana S. Gonzalez-Reiche, Jessica Nardulli, Zain Khalil, Charles Gleason, Eniko Hermann, Komal Srivastava, Emilia Mia Sordillo, Harm van Bakel, Anass Abbad, Florian Krammer, Viviana Simon   +18 more
doaj   +5 more sources

Assessment of human immunity to A/H3N2 influenza subclade K during 2025 emergenceResearch in context [PDF]

EBioMedicine
Summary: Background: Seasonal influenza causes significant morbidity and mortality annually. In 2025, the genetically divergent A/H3N2 K subclade (J.2.4.1) emerged with substantial haemagglutinin mutations.
Ruth Harvey, Ceilidh Welsh, Alexander MP. Byrne, David Greenwood, Phoebe Stevenson-Leggett, Monica Galiano, Dalan Bailey, Yung-Wai Chan, Jacob Boateng, Hannah Wolmuth-Gordon, Heather Whitaker, Kevin E. Brown, Anna Jeffery-Smith, Alex Allen, Gayatri Amirthanlingam, Even Fossum, Elisabeth Lea Vikse, Andreas Rohringer, Olav Hungnes, Karoline Bragstad, Charles Swanton, Bryan Williams, Sonia Gandhi, Steve Gamblin, Edward J. Carr, Nicola S. Lewis, Emma C. Wall, Mary Y. Wu, Giulia Dowgier, Agnieszka Hobbs, Choon Ping Tan, Jarod Zvartau-Hind, Murad Miah, Odiesia Daley, Mauro Miranda, Philip Bawumia, Nicola O’Reilly, Chris Cheshire, Nicholas Wilson, Karen Ambrose, Amy Strange, Gavin Kelly, Svend Kjær, Rupert CL. Beale, Padmasavee Papineni, Tumena Corrah, Richard Gilson   +46 more
doaj   +3 more sources

Influenza A(H3N2) Subclade K: Epidemiology, Molecular Evolution and Vaccine Effectiveness in Europe [PDF]

Pathogens
Background: Influenza A(H3N2) viruses remain a major public health concern due to their rapid antigenic evolution and association with severe disease, particularly among high-risk populations.
Irene Scarvaglieri, Maria Antonia De Francesco, Maria Alberti, Federico Cesanelli, Martina Salvi, Giorgio Tiecco, Francesco Castelli, Eugenia Quiros-Roldan   +7 more
doaj   +4 more sources

Modest protection from vaccination against influenza A(H3N2) subclade K, Beijing, China, 2025/26 season [PDF]

Eurosurveillance
During the early 2025/26 influenza season, influenza A(H3N2) subclade K rapidly predominated in Beijing, China. Using a test-negative design, we estimated influenza vaccine effectiveness (VE) among influenza-like illness outpatients tested between weeks ...
Peng Yang
doaj   +4 more sources

Influenza A(H3N2) Subclade K (J.2.4.1): Molecular Characterization, Antigenic Divergence, and Global Spread During the 2025/26 Season [PDF]

Infectious Disease Reports
Background: Influenza A(H3N2) continues to evolve rapidly, frequently eroding population immunity and challenging seasonal vaccine strain selection. During the 2025/26 season, the A(H3N2) subclade K (J.2.4.1) expanded quickly across multiple regions and ...
Francesco Branda, Nicola Petrosillo, Giancarlo Ceccarelli, Fabio Scarpa, Marta Giovanetti, Massimo Ciccozzi   +5 more
doaj   +3 more sources

Reduced neutralising antibody responses against emerging 2025/26 influenza A(H1N1)pdm09 subclade D.3.1 and A(H3N2) subclade K viruses among healthcare workers, Finland, August to October 2025 [PDF]

Eurosurveillance
During autumn 2025, drifted influenza A(H3N2) subclade K and A(H1N1)pdm09 subclade D.3.1. and D.3.1.1 viruses were detected in Finland. We assessed antibody responses against 2024/25 vaccine and 2025/26 epidemic influenza A strains among 46 Finnish ...
Hanna Nohynek
doaj   +6 more sources

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

Eurosurveillance
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 ...
Jamie Lopez Bernal
doaj   +5 more sources

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

Eurosurveillance
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 ...
Danuta M Skowronski
doaj   +4 more sources

Population immunity, post-vaccine and post-infection antibody responses to influenza A (H3N2) subclade J.2 and K (J.2.4.1) viruses, Hong Kong, 2025 [PDF]

Eurosurveillance
We assessed haemagglutination inhibition (HAI) antibody titres against 2025 influenza A(H3N2) J.2 vaccine reference viruses and the novel subclade K (J.2.4.1) in age-stratified Hong Kong sera (collected May–July 2025), vaccine recipients and sera from ...
Malik Peiris
doaj   +4 more sources