New Flu Virus With Pandemic Potential Found In Pigs

October 13, 2020

The last thing we need in COVID-19 is another pandemic. But scientists in China are now warning that they have discovered a new flu virus in pigs that could cause a future flu pandemic.

The virus, known as G4 EA H1N1, is a genetic mix of the H1N1 “swine flu” and other flu viruses that caused the 2009 flu pandemic. A study published Monday (June 29) in the Proceedings of the National Academy of Sciences found evidence that G4 EA H1N1 infected workers on Chinese hog farms. But importantly, according to CNN, there is no indication that the virus is spreading from person to person.

The authors caution that the virus is not an immediate health threat, according to the BBC. But they say that controlling this virus in pigs and monitoring humans for signs of it “should be implemented urgently.”

According to the Centers for Disease Control and Prevention, the 2009 H1N1 flu pandemic is estimated to have killed between 151,700 and 575,400 people worldwide and infected up to 1.4 billion people. After it ended, the virus became one of the seasonal flu viruses that circulate among people every year. Eventually, the virus must have spread from humans back to pigs, where it mixed with other flu viruses to create G4 EA H1N1, according to CNN.

In the new study, researchers analyzed nasal swabs from nearly 30,000 pigs collected from slaughterhouses in 10 Chinese provinces between 2011 and 2018. From these samples, they found that nearly 180 different strains of influenza virus infected pigs.

However, many of these viruses did not circulate for long. They appeared one year and were gone the next. But G4 EA H1N1 kept appearing and has been the main influenza strain in pigs since 2016, the authors said.

Tests in laboratory petri dishes showed that the virus could bind to receptors on human cells and replicate efficiently in human airway cells.

What’s more, when the researchers analyzed blood samples from 338 swine workers, they found that about 10 percent had antibodies to the virus, suggesting that they had been exposed to it. For younger workers between the ages of 18 and 35, the percentage of positive test results (known as the positivity rate) was 20 percent, the authors said, suggesting that younger adult workers are at higher risk of infection.

While the authors say the virus has the “essential characteristics of a candidate pandemic virus,” experts caution that this does not necessarily mean it will cause a future pandemic.

“Our understanding of what constitutes a potential pandemic flu strain is limited,” tweeted Angela Rasmussen, a virologist at Columbia University.” Sure, this virus meets many basic criteria, but it won’t necessarily cause the hypothetical 2020 flu pandemic, or even be the dominant strain in humans.”

Still, the new study is “a reminder that we are constantly at risk of the emergence of new zoonotic pathogens,” said James Wood, head of the University of Cambridge’s Department of Veterinary Medicine, who was not involved in the study, in a statement. In particular, “farmed animals, which have more contact with humans than with wildlife, may act as a source of important pandemic viruses,” Wood said.