Effectiveness of BA.1-and BA.4/BA. 5-Containing Bivalent COVID-19 mRNA Vaccines Against Symptomatic SARS-CoV-2 Infection During the BA.5-Dominant Period in Japan

In this multicenter, prospective, test-negative, case-control study in Japan, the effectiveness of both BA.1-containing and BA.4/BA.5-containing bivalent coronavirus disease 2019 mRNA vaccines against symptomatic infection during the BA.5-dominant period was high compared with no vaccination (65% and 76%) and moderate compared with monovalent vaccines administered over half a year earlier (46% combined). In this multi-center study in Japan, the effectiveness of both BA.1-containing and BA.4/BA.5-containing bivalent vaccines against symptomatic infection during the BA.5-dominant period was high compared to no vaccination (65%/76%) and moderate compared to monovalent vaccines >6 months before (46% combined).