KEY POINTS

  • A mutation of the H1N1 swine flu virus looms as a new pandemic threat
  • This swine flu variant is called "G4 EA H1N1"
  • It has infected some Chinese pig farm workers but person-to-person transmission hasn't been detected, yet

A mutation of the H1N1 swine flu virus identified by a new study as having "all the essential hallmarks of a candidate pandemic virus," has been infecting pig farm workers in China since 2016.

This new strain is called "G4 EA H1N1" and is the subject of a peer-reviewed study published online Monday in the journal Proceedings of the National Academy of Sciences (PNAS). The study was done by a team of Chinese researchers and is titled, "Prevalent Eurasian avian-like H1N1 swine influenza virus with 2009 pandemic viral genes facilitating human infection."

“G4 viruses have all the essential hallmarks of a candidate pandemic virus,” said the study.

The scientists are reporting the G4 EA H1N1 virus is currently only transmissible between pigs. Which means, as of now, it can't be transmitted from person-to-person; the Chinese pig farm workers sick by the virus were infected by sick pigs.

The study said this new strain of the H1N1 swine flu virus is spreading silently among Chinese workers on pig farms. It urges the Chinese government to urgently control the spread of the virus in pigs. More important, the study said closely monitoring human populations “should be urgently implemented.”

The study said the latest evidence indicates the G4 EA H1N1 virus is a growing problem in pig farms. It also said the widespread circulation of G4 viruses in pigs will inevitably increase their exposure to humans, making infections more likely. More worryingly, the incidence of G4 viruses in farmed Chinese pigs exhibiting respiratory symptoms began a sharp jump after 2014.

The need to urgently get G4 EA H1N1 under control is necessary because it replicates and spreads quickly in human airways, much like SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2), the virus that causes COVID-19.

Thankfully, so far G4 EA H1N1 has infected its few victims without causing disease. Chinese health experts, however, are afraid this might no longer be the case when G4 EA H1N1 further mutates.

The U.S. is aware of this new virus but sees no immediate threat, however. Dr. Anthony Fauci, Director of the National Institute of Allergy and Infectious Diseases (NIAID), on Tuesday said the G4 EA H1N1 isn't an “immediate threat.” He added that the new virus, however, is “something we need to keep our eye on the just the way we did with in 2009 with the emergence of the swine flu.”

Workers wearing protective suits drive pigs to kill at a farm confirmed to have been infected with African swine fever in Paju, South Korea Workers wearing protective suits drive pigs to kill at a farm confirmed to have been infected with African swine fever in Paju, South Korea Photo: AFP / Yelim LEE

A key next step in monitoring G4 ES H1N1 is to find out if any of the infected workers at pig farms had contracted the virus from humans. It also has to be ascertained if any of these people had spread the virus to their families, said Dr. Li-Min Huang, director of the Division of Pediatric Infectious Disease's at the National Taiwan University Hospital.

“It’s a very important study, and the virus looks quite dangerous,” noted Dr. Huang. “We need to be worried about any disease with the potential to spread human to human.”