Genetic Characterization of Two Human Cases Infected with the Avian Influenza A (H5N6) Viruses — Guangxi Zhuang Autonomous Region, China, 2021

WHAT IS KNOWN ABOUT THIS TOPIC? H5N6 has replaced H5N1 as a dominant avian influenza virus (AIV) subtype in southern China. The increasing genetic diversity and geographical distribution of H5N6 pose a serious threat to the poultry industry and human health. WHAT IS ADDED BY THIS REPORT? A total of 2 cases of H5N6 that occurred from February 2021 to July 2021 in Guangxi, China were reported in this study. Phylogenetic analysis of gene was constructed, and some mutations of HA gene, PB2 gene, PA gene, M1 gene, NS1 gene, the receptor-binding site were detected. The evolutionary origins of the internal genes were different. WHAT ARE THE IMPLICATIONS FOR PUBLIC HEALTH PRACTICE? As a multi-source reassortant virus, the H5N6 highly pathogenic AIV is continuously evolving. There is an urgent need to strengthen the surveillance of drug-resistant strains and novel variants.