Chinese study warns new swine flu virus has 'pandemic' potential

Researchers in China have discovered a new type of swine flu that could be capable of triggering a pandemic, according to a study published on Monday in the US science journal Proceedings of the National Academy of Sciences (PNAS). Some experts say that the virus does not currently pose an imminent threat.

The virus has become more infectious to humans and needs to be watched closely in case it becomes a potential "pandemic virus," according to the authors, who include scientists at Chinese universities and China's Center for Disease Control and Prevention.

From 2011 to 2018, researchers took 30,000 nasal swabs from pigs in slaughterhouses in 10 Chinese provinces and in a veterinary hospital, allowing them to isolate 179 swine flu viruses.

Among those viruses, researchers found a "G4" strain of H1N1 that has "all the essential hallmarks of a candidate pandemic virus." The researchers carried out various experiments, including on ferrets, which experience flu symptoms similar to humans.

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Pig farmers infected

Following the tests, researchers found that G4 was highly infectious, replicating in human cells and causing more serious symptoms in ferrets than other viruses.

They also found that pig farm workers had elevated levels of the virus in their blood. According to blood tests, which showed antibodies created by exposure to the virus, 10.4% of pig farmers had already been infected by the virus, and as much as 4.4% of the general population also appeared to have been exposed.

Tests also showed that any immunity humans gain from exposure to the seasonal flu does not provide protection from the G4 strain.

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Calls for 'urgent monitoring'

"Close monitoring in human populations, especially the workers in the swine industry, should be urgently implemented," the paper said. "It is of concern that human infection of G4 virus will further human adaptation and increase the risk of a human pandemic."

The study also focused on the possibility of viruses crossing the species barrier into humans, particularly in densely populated regions in China, where millions live in close proximity to farms, breeding facilities, slaughterhouses and wet markets.

Evidence shows that the virus has already been passed from animals to humans. However, there is no evidence yet that it could be passed from humans to humans. Some researchers believe that there is no imminent threat to humans.

"Every indication is that the G4 virus would have to undergo some evolutionary change to spread readily in people, and it may never do that," tweeted Carl Bergstrom, a biologist at the University of Washington.

Officials chime in

World Health Organization (WHO) spokesman Christian Lindmeier said that the WHO will read the study carefully, and that it was important to collaborate on findings and keep tabs on animal populations.

"It also highlights we cannot let our guard down on influenza and need to be vigilant and continue surveillance even in the coronavirus pandemic," said Lindmeier.

"China is closely following the developments in regard to this matter. We will take all necessary measures to prevent the spread and outbreak of any virus," Chinese Foreign Ministry spokesman Zhao Lijian said.

lc/rs (Reuters, AFP)