AbstractA new H3N2 variant (named subclade K) possesses several key hemagglutinin substitutions and is circulating widely during the 2025-2026 influenza season. We sought to determine whether the 2025-2026 seasonal influenza vaccine elicits antibodies in humans that recognize this variant. We found that H3N2 subclade K viruses are antigenically advanced; however, the 2025-2026 seasonal influenza vaccine elicited antibodies in many individuals that efficiently recognized these viruses. Thus, the current seasonal influenza vaccine likely will be partially effective at preventing illness associated with H3N2 subclade K virus infections.
Liu et al. (2026) studied this question.