Additionally, Sanz-Muñoz et al. obtained evidence for the existence of low level basal heterosubtypic immunity against H5N1 HPAIV subtypes in humans that could be increased by seasonal influenza vaccination using a recombinant H1N1 influenza virus expressing HA and NA proteins of H5N1 HPAIV A/chicken/Egypt/F71-F114C/2022 (clade 2.3.4.4b) [17] – however, bovine H5N1 HPAIV was not tested. This evidence concerns the gene XK and influenza.