Cross-sectional study on protective antibodies against influenza A virus subtypes and cross-protection against influenza A(H3N2) subclade K, Portugal, August 2025
The 2025/26 season was marked by co-circulation of influenza A subtypes, with the first detection of A(H3N2) subclade K in September 2025. In August 2025 in Portugal, 14.8% (95% CI: 12.2-17.8) of 886 persons tested had cross-protective antibodies against this subclade. The overall seroprevalence against circulating A(H1N1)pdm09 strains was 28.1% (95% CI: 24.4-32.0). These data highlight the presence of previous cross-reactive antibodies and the possible advantage of vaccination in the extent of detectable antibodies against influenza viruses.
Authors
- S. da Silva
- Nuno Verdasca (ORCID: https://orcid.org/0000-0002-4673-5411)
- Raquel Guiomar
- Daniela Dias
- Licínia Gomes
- Baltazar Nunes
- Camila Henriques
- Ana Paula Rodrigues
Institutions
- National Institute of Health Dr. Ricardo Jorge (PT)
- Universidade Nova de Lisboa (PT)
Publication Details
- Journal
- Eurosurveillance
- Published
- 2026-02-12
- DOI
- https://doi.org/10.2807/1560-7917.es.2026.31.6.2600070
- Primary Topic
- Influenza Virus Research Studies
- Type
- article
- Field-Weighted Citation Impact
- 0.00