Two novel reassortant highly pathogenic avian influenza viruses (H5N1) clade 2.3.4.4b.2 were identified in dead migratory birds in China in November 2021. The viruses probably evolved among wild birds through different flyways connecting Europe and Asia. Their low antigenic reaction to vaccine antiserum indicates high risks to poultry and to public health.
Keywords: China; H5N1; antigenic variation; clade 2.3.4.4b; genetic origin; highly pathogenic avian influenza virus; influenza; migratory bird; phylogeography; reassortant; vaccine-preventable diseases; viruses; zoonoses.