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
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 virologically confirmed subclade J.2.2 or K infections. In contrast to mono-specific ferret sera, human sera with high J.2 HAI titres cross-reacted strongly with subclade K. Recombinant haemagglutinin- or egg-based standard dose J.2 A(H3N2) vaccines boosted geometric mean titres to K virus 5.6-fold and 2.6-fold, respectively.
Authors
- Rwk Wong (ORCID: https://orcid.org/0000-0002-1941-388X)
- Leo C.H. Tsang
- Tsz Chun Kwan
- Chak K. Chan (ORCID: https://orcid.org/0000-0001-9687-8771)
- Jin Li (ORCID: https://orcid.org/0000-0002-6131-456X)
- X.R. Huang
- KL Tsang
- Samuel MS Cheng
- Nancy HL Leung
- Benjamin J Cowling
- Eunice Y Shiu
- Leo LM Poon
- Malik Peiris
- Natalie KM Kwok
- Niki YM Au
Institutions
- Hong Kong Science and Technology Parks Corporation (HK)
- University of Hong Kong (HK)
Publication Details
- Journal
- Eurosurveillance
- Published
- 2026-03-12
- DOI
- https://doi.org/10.2807/1560-7917.es.2026.31.10.2600185
- Primary Topic
- Influenza Virus Research Studies
- Type
- article
- Field-Weighted Citation Impact
- 0.00