Abstract
In 2025, a mutated H3N2 lineage, subclade K, emerged, showing high activity in many regions. Mutations in the hemagglutinin (HA) may affect cell entry and antibody-mediated neutralisation. Using pseudovirus particles, we show that subclade K-HA drives augmented entry into certain cell lines and displays significant antibody evasion. Both phenotypes were linked to mutation A186D. Influenza vaccination significantly boosted H3N2 subclade K neutralisation, suggesting that current vaccines may provide considerable protection.