A cell culture-derived whole-virus H5N1 vaccine induces long-lasting cross-clade protective immunity in mice which is augmented by a homologous or heterologous booster vaccination

►Vero-derived whole-virus H5N1 vaccine induces long-lasting humoral and cellular immunity. ► One or two priming immunizations provide long-term protection against wild-type H5N1 challenge. ► Humoral and cellular immunity substantially increased by homologous or heterologous booster. ► Broadest protection provided by heterologous prime-boost immunization regimen.