Evolutionary characterization of clades 2.3.4.4 H5N6 and 2.3.2.1C H5N1 HPAI viruses in Vietnam (2013–2019) revealed distinct reassortants from distant spillovers

Highly pathogenic avian influenza (HPAI) H5Nx viruses have continually undergone multiple evolutionary dynamics for the generation of various clades, subclades, and genotypes where 2.3.2.2c, and 2.3.4.4 become predominant and co-circulating in Vietnam from 2014 to date.