Recently, the first human case of acute respiratory distress syndrome caused by the H3N8 subtype avian influenza virus (AIV) (A/Henan/4–10CNIC/2022, Henan4–10) was documented in this journal. 1 Cheng D. Dong Y. Wen S. Shi C. A child with acute respiratory distress syndrome caused by avian influenza H3N8 virus.

J Infect. 2022; 85 (May 13PubMed PMID: 35577072. Epub 2022/05/17): 174-211

The H3N8 subtype AIV was isolated from 4-year-old children who had contact with chickens and crows in Henan, China. Meanwhile, this journal has previously documented that wild bird origin H3N8 AIV has the binding affinity to both a-2,3 and a-2,6 receptors. 2 Li Y. Li P. Xi J. Yang J. Wu H. Zhang Y. et al. Wild bird-origin H3N8 avian influenza virus exhibit well adaptation in mammalian host.

J Infect. 2022; 84 (AprPubMed PMID: 34953909. Epub 2021/12/27): 579-613

Their results suggested that H3N8 AIV can replicate well and exhibit pathogenicity in BALB/c mice without prior adaptation. Previous surveillance studies conducted in wild birds and live bird markets indicated that the H3N8 subtype is one of the most common subtypes in domestic ducks and has undergone extensive reassortment with other endemic subtypes in waterfowl. 3 Deng G. Tan D. Shi J. Cui P. Jiang Y. Liu L. et al. Complex reassortment of multiple subtypes of avian influenza viruses in domestic ducks at the Dongting Lake Region of China.

J Virol. 2013; 87 (SepPubMed PMID: 23804642. Pubmed Central PMCID: PMC3754128. Epub 2013/06/28): 9452-9462

Moreover, the H3N8 virus is one of the best mammalian adapted AIVs and has been reported in various species, including dogs, horse, pig, harbor seal, gray seal, and donkeys. 4 Karlsson E.A. Ip H.S. Hall J.S. Yoon S.W. Johnson J. Beck M.A. et al. Respiratory transmission of an avian H3N8 influenza virus isolated from a harbour seal.

Nat Commun. 2014; 5 (Sep 3PubMed PMID: 25183346. Pubmed Central PMCID: PMC4801029. Epub 2014/09/04): 4791

Those studies suggested that predominantly H3N8 AIVs are inclined to cross species barriers and pose a significant threat to human and animal health.