Extended influenza seasons in Australia and New Zealand in 2025 due to the emergence of influenza A(H3N2) subclade K viruses
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 (H3N2)-like virus and previously circulating subclade J viruses. Subclade K viruses have since been detected in over 34 countries and appear to have spread globally, except in South America. It is thus likely that they will further expand during the northern hemisphere winter 2025/26 season.
Authors
- Timothy J. Wood (ORCID: https://orcid.org/0000-0001-9177-704X)
- Yi‐Mo Deng (ORCID: https://orcid.org/0000-0003-2177-8308)
- Q. Sue Huang (ORCID: https://orcid.org/0000-0002-3923-5195)
- Saira Hussain (ORCID: https://orcid.org/0000-0002-0545-244X)
- Tanya Diefenbach‐Elstob (ORCID: https://orcid.org/0000-0002-7784-5111)
- Clyde Dapat (ORCID: https://orcid.org/0000-0002-7616-4680)
- Allen Cheng (ORCID: https://orcid.org/0000-0003-3152-116X)
- Heidi Peck (ORCID: https://orcid.org/0000-0002-3651-2839)
- Lauren Jelley (ORCID: https://orcid.org/0000-0001-5993-6266)
- Annaleise R. Howard‐Jones (ORCID: https://orcid.org/0000-0002-9756-2813)
- Jessica E. Miller (ORCID: https://orcid.org/0000-0002-1806-1894)
- Ian Barr (ORCID: https://orcid.org/0000-0002-7351-418X)
- Philip N Britton (ORCID: https://orcid.org/0000-0002-2993-6000)
- Tegan Slater
Institutions
- GNS Science (NZ)
- The University of Sydney (AU)
- The University of Melbourne (AU)
- Taronga Conservation Society Australia (AU)
- Children's Hospital at Westmead (AU)
- Victorian Infectious Diseases Reference Laboratory (AU)
- Monash Health (AU)
- Monash University (AU)
Publication Details
- Journal
- Eurosurveillance
- Published
- 2025-12-11
- DOI
- https://doi.org/10.2807/1560-7917.es.2025.30.49.2500894
- Citations
- 15
- Primary Topic
- Influenza Virus Research Studies
- Type
- article
- Field-Weighted Citation Impact
- 20.31