Panzootic HPAIV H5 and risks to novel mammalian hosts

The H5 subtype of highly pathogenic avian influenza viruses represents a significant challenge to animal and human health. H5 clade 2.3.4.4b viruses have experienced an unprecedented global spread, coupled with remarkable genetic plasticity for adaptation in birds and mammals. Although human infections remain very limited, the establishment in wild, marine, and farmed animals, including recently dairy cattle, is of concern. The role of mammalian hosts as intermediaries for zoonotic or even pandemic influenza A viruses should not be underestimated. In order to mitigate the zoonotic risk and be adequately prepared, it is essential to understand and monitor the dynamics of HPAIV H5 at the avian-mammal interface.