In China, influenza A(H7N9) virus appeared in 2013, then mutated into a highly pathogenic virus, causing outbreaks among poultry and cases in humans. Since September 2017, extensive use of the corresponding vaccine, H7-Re1, successfully reduced virus prevalence. However, in 2019, a novel antigenic variant emerged, posing considerable economic and public health threats.A.
Keywords: China; H7N9; HPAI; Influenza virus; antigenicity; highly pathogenic avian influenza; influenza; variant; viruses.