Inactivated and adjuvanted whole-virion clade 2.3.4 H5N1 pre-pandemic influenza vaccine possesses broad protective efficacy against infection by heterologous clades of highly pathogenic H5N1 avian influenza virus in mice

► Alum-adjuvanted H5N1 rgAnhui (clade 2.3.4) vaccine induced broad cross-reactive neutralizing antibodies. ► The rgAnhui vaccine elicited protective immunity in mice against challenge infections with heterologous clade H5N1 viruses. ► Vaccine formulation with alum adjuvant allowed sparing vaccine antigen.