Chinese researchers have discovered a new type of swine flu that can infect humans and has the potential to cause a future pandemic.
The disease, which researchers called G4 EA H1N1, is genetically descended from the H1N1 swine flu that caused a pandemic in 2009. The researchers are concerned that it could mutate further and can spread easily from person to person and trigger a global outbreak, though scientists have cautioned that the virus does not pose an immediate global health threat.
G4 EA H1N1 has been common on China’s pig farms since 2016 and replicates efficiently in human airways, according to the study published on Monday. So far, it has infected some people without causing disease, but health experts fear that could change without warning.
G4 now shows “all the essential hallmarks of a candidate pandemic virus,” said the study, published in the scientific journal Proceedings of the National Academy of Sciences (PNAS).
But Dr. Angela Rasmussen, a virologist at Columbia University’s public health school, warned the public not to “freak out.”
“Our understanding of what is a potential pandemic influenza strain is limited,” she posted on Twitter. “Sure, this virus meets a lot of the basic criteria but it’s not for sure going to cause a hypothetical 2020 flu pandemic, or even be a dominant strain in humans.”
From 2011 to 2018, they collected more than 30,000 nasal swab samples from pigs in slaughterhouses and veterinary teaching hospitals across 10 Chinese provinces.
Researchers identified 179 swine influenza viruses, from the samples but not all of them posed a concern. Some only showed up one year out of the program’s seven, or eventually declined to non-threatening levels.
Further tests showed that G4 can infect humans by binding to our cells and receptors, and it can replicate quickly inside our airway cells. And though G4 holds H1N1 genes, people who have received seasonal flu vaccines won’t have any immunity.
Professor Kin-Chow Chang, who works at Nottingham University in the UK, told the BBC: “Right now we are distracted with coronavirus and rightly so. But we must not lose sight of potentially dangerous new viruses.”
A World Health Organization spokeswoman said: “Eurasian avian-like swine influenza viruses are known to be circulating in the swine population in Asia and to be able to infect humans sporadically. Twice a year during the influenza vaccine composition meetings, all information on the viruses is reviewed and the need for new candidate vaccine viruses is discussed. We will carefully read the paper to understand what is new.
“It also highlights that we cannot let down our guard on influenza; we need to be vigilant and continue surveillance even during the COVID-19 pandemic.”