Scientists affiliated with the Shandong Agricultural University and the Chinese National Influenza Center have identified a derivative of H1N1 virus designated at G4.  This specific virus was consistently isolated over a period extending from 2011 to 2018 involving surveillance of hogs delivered to slaughterhouses. A total of 179 influenza viruses were isolated from 30,000 nasal swabs, most of which were only present for a season.

Researchers noted that the G4 virus reoccurred annually and showed increased incidence after 2016.  The G4 virus contains H1N1 genes and can bind to human cells in vitro.  Serologic studies in Hebei and Shandong Provinces demonstrated antibodies among hog farmers and slaughterhouse workers.  As yet, there is no evidence that the virus can be transmitted among humans.

It is absolutely essential that viruses of hogs should be constantly surveyed to detect the emergence of strains which are potentially pathogenic to humans. In 2019 the H1N1 influenza pandemic was responsible for as many as 500,000 fatalities worldwide.  The G4 virus has developed by interchange of genetic materials that occurs readily in very large populations of susceptible animals or humans in close association.

 International cooperation with coordination of research and diagnostic activities by individual nations is critical to recognizing the emergence of an epidemic strain of influenza or other viral diseases.  The emergence of SARS, MERS, and most recently COVID-19 demonstrate the need for international cooperation and communication with coordination by apolitical agencies, such as the World Health Organization and the World Organization for Animal Health.