H7N3 is a highly pathogenic avian influenza virus. H7N3 is circulating in poultry in Mexico since 2002 and vaccination has been used to control the disease. There have been four unrelated outbreaks of H7N3 subtype HPAI in poultry in the American continents, including outbreaks in Chile, Canada, and Mexico . The Mexican H7N3 HPAI virus has been causing outbreaks in commercial chickens and backyard poultry in Mexico since its first detection in 2012. Despite the control measures undertaken, cases of H7N3 HPAI in poultry have been repeatedly documented and two confirmed cases of human infection were reported from poultry workers.
Andrey Rekstin. Live Attenuated Influenza H7N3 Vaccine is Safe, Immunogenic and Confers Protection in Animal Models. The Open Microbiology Journal.2014
Sungsu Youk. Rapid evolution of Mexican H7N3 highly pathogenic avian influenza viruses in poultry. PLOS ONE.2019