Long-Term Epidemiology and Evolution of Swine Influenza Viruses, Vietnam

Influenza A viruses are a One Health threat because they can spill over between host populations, including among humans, swine, and birds. Surveillance of swine influenza virus in Hanoi, Vietnam, during 2013-2019 revealed gene pool enrichment from imported swine from Asia and North America and showed long-term maintenance, persistence, and reassortment of virus lineages. Genome sequencing showed continuous enrichment of H1 and H3 diversity through repeat introduction of human virus variants and swine influenza viruses endemic in other countries. In particular, the North American H1-d1a strain, which has a triple-reassortant backbone that potentially results in increased human adaptation, emerged as a virus that could pose a zoonotic threat. Co-circulation of H1-d1a viruses with other swine influenza virus genotypes raises concerns for both human and animal health.

Automated summary

Surveillance of swine influenza virus in Hanoi, Vietnam, from 2013 to 2019 revealed continuous enrichment and reassortment of virus lineages, with imported swine from Asia and North America playing a significant role. The introduction of human virus variants and swine influenza viruses endemic in other countries contributed to the diversity of H1 and H3 subtypes. The emergence of the North American H1-d1a strain with increased human adaptation poses a zoonotic threat, raising concerns for both human and animal health.