This study reported the identification of three human monoclonal antibodies that protected mice against lethal challenge from two antigenically distinct lineages of influenza B viruses that are responsible for a large part of the annual flu burden. The authors showed that two antibodies (CR8033 and CR8071) recognized distinct conserved epitopes in the head region of influenza B haemagglutinin, whereas CR9114 bound to a conserved epitope in the haemagglutinin stem and protected mice against both influenza A and B viruses.