tetano
Editor, Senior Moderator
EBioMedicine
. 2026 Jun 12:129:106321.
doi: 10.1016/j.ebiom.2026.106321. Online ahead of print.
Seasonal vaccine-induced immunity shows preserved cross-reactivity to H3N2 subclade K in adults
Adria Wilson[SUP] 1 [/SUP], Brian Lerman[SUP] 1 [/SUP], Reima Ramsamooj[SUP] 1 [/SUP], Jacob Mischka[SUP] 1 [/SUP], Jordan Ehrenhaus[SUP] 1 [/SUP], Ashley Aracena[SUP] 1 [/SUP], Yusuf Figueroa[SUP] 1 [/SUP], Keith Farrugia[SUP] 2 [/SUP], Ana S Gonzalez-Reiche[SUP] 2 [/SUP], Jessica Nardulli[SUP] 1 [/SUP], Zain Khalil[SUP] 2 [/SUP], Charles Gleason[SUP] 1 [/SUP], Eniko Hermann[SUP] 3 [/SUP], Komal Srivastava[SUP] 1 [/SUP], Emilia Mia Sordillo[SUP] 4 [/SUP], Harm van Bakel[SUP] 5 [/SUP], Anass Abbad[SUP] 6 [/SUP], Florian Krammer[SUP] 7 [/SUP], Viviana Simon[SUP] 8 [/SUP]
Affiliations
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.
Methods: We measured antibody responses in matched human pre- and post-vaccination sera, selected from two observational cohort studies of adults, against both a vaccine-like as well as subclade K isolates.
Findings: Pre-existing immunity to subclade K variants was noted with seasonal influenza vaccination further boosting titres two-fold against subclade K and three-fold against the vaccine-like strain, consistent with limited antigenic divergence between subclade K isolates and the vaccine. These findings contrast with ferret-based predictions of marked antigenic drift and align with the observed vaccine effectiveness in adults.
Interpretation: Our results underscore the importance of incorporating human serologic data in influenza surveillance to better inform vaccine strain selection and anticipate vaccine performance in immunologically experienced populations.
Funding: NIAID Centers for Excellence in Influenza Research and Response (75N93021C00014); NIAID VIVA HIPC (U19 AI168631); Mount Sinai Center for Vaccine Research and Pandemic Preparedness; institutional support from the Mount Sinai Center for Vaccine Research and Pandemic Preparedness and the Medical University of Vienna.
Keywords: Antigenic drift; Cross-reactive immunity; Haemagglutination inhibition antibodies; Influenza A H3N2 subclade K; Neutralising antibodies; Vaccine effectiveness.
. 2026 Jun 12:129:106321.
doi: 10.1016/j.ebiom.2026.106321. Online ahead of print.
Seasonal vaccine-induced immunity shows preserved cross-reactivity to H3N2 subclade K in adults
Adria Wilson[SUP] 1 [/SUP], Brian Lerman[SUP] 1 [/SUP], Reima Ramsamooj[SUP] 1 [/SUP], Jacob Mischka[SUP] 1 [/SUP], Jordan Ehrenhaus[SUP] 1 [/SUP], Ashley Aracena[SUP] 1 [/SUP], Yusuf Figueroa[SUP] 1 [/SUP], Keith Farrugia[SUP] 2 [/SUP], Ana S Gonzalez-Reiche[SUP] 2 [/SUP], Jessica Nardulli[SUP] 1 [/SUP], Zain Khalil[SUP] 2 [/SUP], Charles Gleason[SUP] 1 [/SUP], Eniko Hermann[SUP] 3 [/SUP], Komal Srivastava[SUP] 1 [/SUP], Emilia Mia Sordillo[SUP] 4 [/SUP], Harm van Bakel[SUP] 5 [/SUP], Anass Abbad[SUP] 6 [/SUP], Florian Krammer[SUP] 7 [/SUP], Viviana Simon[SUP] 8 [/SUP]
Affiliations
- PMID: 42284681
- DOI: 10.1016/j.ebiom.2026.106321
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.
Methods: We measured antibody responses in matched human pre- and post-vaccination sera, selected from two observational cohort studies of adults, against both a vaccine-like as well as subclade K isolates.
Findings: Pre-existing immunity to subclade K variants was noted with seasonal influenza vaccination further boosting titres two-fold against subclade K and three-fold against the vaccine-like strain, consistent with limited antigenic divergence between subclade K isolates and the vaccine. These findings contrast with ferret-based predictions of marked antigenic drift and align with the observed vaccine effectiveness in adults.
Interpretation: Our results underscore the importance of incorporating human serologic data in influenza surveillance to better inform vaccine strain selection and anticipate vaccine performance in immunologically experienced populations.
Funding: NIAID Centers for Excellence in Influenza Research and Response (75N93021C00014); NIAID VIVA HIPC (U19 AI168631); Mount Sinai Center for Vaccine Research and Pandemic Preparedness; institutional support from the Mount Sinai Center for Vaccine Research and Pandemic Preparedness and the Medical University of Vienna.
Keywords: Antigenic drift; Cross-reactive immunity; Haemagglutination inhibition antibodies; Influenza A H3N2 subclade K; Neutralising antibodies; Vaccine effectiveness.