Swine flu virus in China: what is G4 EA H1N1 and why does it have pandemic potential?

A study published in the Proceedings of the National Academy of Sciences of the United States of America, focuses on the study an influenza found in Chinese pigs called G4 EA H1N1. Researchers say the virus is a blend of similar strains found in European and Asian birds, the source of the H1N1 strain that caused the 2009 pandemic and North American H1N1.

It was reported that at least two cases of G4 infections of humans have been documented, but the virus cannot be transmitted from person to person. Influenza viruses often jump from pigs to humans but researchers say G4’s inclusion of genes from the 2009 H1N1 pandemic “may promote the virus adaptation,” allowing for human-to-human transmission.

During their research scientists analyzed almost 30,000 swabs collected from pigs at slaughterhouses in 10 Chinese provinces between 2011 and 2018. After testing each swab they found 179 swine influenza viruses, the majority which were G4.

G4 "has shown a sharp increase since 2016"

“G4 virus has shown a sharp increase since 2016, and is the predominant genotype in circulation in pigs detected across at least 10 provinces. All of this evidence indicates that G4 EA H1N1 virus is a growing problem in pig farms, and the widespread circulation of G4 viruses in pigs inevitably increases their exposure to humans,” the researchers said.

Once the research was published further monitoring of farms and workers was called for as increased transmission could cause the virus to adapt and become a new pandemic. However, other scientists who analyzed the study said the chance of another pandemic due to G4 is unlikely.