The modular binding sites on the influenza A(H3N2) hemagglutinin protein are under significant pressure to acquire mutations in order to evade human antibody recognition. Analysis of these hemagglutinin epitopes in the strains circulating during 2017/18 and early 2018/19 identified the emergence of a new antigenic cluster that has grown from 4% of circulating strains to 11%. We regressed our module-based antigenic distance, pepitope, with A(H3N2) vaccine effectiveness from recent studies conducted by the US Centers for Disease Control and Prevention (r2?=?0.92), and we used this to estimate that the 2018/19 vaccines will protect against most circulating A(H3N2) strains. The pEpitope model is useful for A(H3N2) influenza vaccine virus selection and development, and it has the potential to aid national or regional regulatory authorities in making geographically localized decisions.