Seasonal vaccine-induced immunity shows preserved cross-reactivity to H3N2 subclade K in adultsResearch in context [PDF]
EBioMedicineSummary: 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 +18 more
doaj +6 more sources
Influenza A(H3N2) Subclade K: Epidemiology, Molecular Evolution and Vaccine Effectiveness in Europe [PDF]
PathogensBackground: 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 +7 more
doaj +5 more sources
Emergence of influenza A(H3N2) subclade K in northeast Ohio in autumn 2025 [PDF]
Journal of Clinical MicrobiologyHannah Wang, Daniel D Rhoads, Ted Ross
exaly +6 more sources
Assessment of human immunity to A/H3N2 influenza subclade K during 2025 emergenceResearch in context [PDF]
EBioMedicineSummary: 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 +46 more
doaj +3 more sources
Reduced T cell epitope cross-conservation and immunogenic potential is associated with emergence of a dominant influenza subclade K in 2025 [PDF]
Human Vaccines & ImmunotherapeuticsSubclade K is a newly emergent influenza A/H3N2 strain that became the dominant strain circulating globally; more than 90% of influenza A virus (IAV) cases in 2025–26 were subclade K.
Andres H. Gutierrez +3 more
doaj +3 more sources
Extended influenza seasons in Australia and New Zealand in 2025 due to the emergence of influenza A(H3N2) subclade K viruses [PDF]
EurosurveillanceIn 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 ...
Ian G. Barr
doaj +4 more sources
Modest protection from vaccination against influenza A(H3N2) subclade K, Beijing, China, 2025/26 season [PDF]
EurosurveillanceDuring 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 ReportsBackground: 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 +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]
EurosurveillanceDuring 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
Northern Hemisphere 2025/26 influenza vaccine effectiveness during months with influenza A(H3N2) subclade K predominance— Suzhou, Eastern China [PDF]
International Journal of Infectious DiseasesDuring this 2025/26 Northern Hemisphere influenza season, the predominant influenza A(H3N2) subclade K virus has binding site mutations and postvaccine sera reduced inhibition, raising concerns about antigenic differences with available vaccines.
Pengwei Cui +18 more
doaj +4 more sources