Protective efficacy of an inactivated chimeric H7/H5 avian influenza vaccine against highly pathogenic avian influenza H7N9 and clade 2.3.4.4 H5 viruses.

•We generated a novel chimeric H7/H5 virus expressing HA1 of the H7N9 virus and HA2 of the H5N6 virus.•The chimeric PR8-H7/H5 induced cross-reactive hemagglutination inhibition antibodies against H7 virus only.•The chimeric PR8-H7/H5 induced serum-neutralizing antibodies against both H7 and H5 viruses.•The chimeric PR8-H7/H5 significantly reduced virus shedding in immunized chickens.•The chimeric PR8-H7/H5 protected chickens against lethal challenge with H7N9 and H5N6 viruses.