- Researchers in China have discovered a new form of swine flu that can infect humans, and they believe it has the potential to cause a future pandemic.
- This swine flu has been dubbed the G4 virus and it’s related to the H1N1 flu that caused widespread illness in 2009.
- Infectious disease doctors explain what we know about the G4 virus so far, and why the general public shouldn’t worry about it just yet.
Researchers in China have found a new form of swine flu that can infect humans—and they say it has the potential to cause another pandemic in the future. The swine flu, which has been dubbed the G4 virus, is related to the H1N1 flu that caused widespread illness in 2009.
The G4 virus is the subject of a new study published in the journal Proceedings of the National Academy of Sciences (PNAS). For the study, researchers collected more than 30,000 nasal swab samples from pigs in slaughterhouses and veterinary teaching hospitals in 10 Chinese provinces from 2011 to 2018. The researchers identified nearly 180 types of swine flu viruses, but only some were concerning. One of them was the G4 virus, which kept resurfacing each year, even when other types of swine flu decreased or went away with time.
When the scientists tested the virus, they discovered that it can infect people by binding to human cells and receptors. It can also replicate (i.e. grow) quickly inside human airway cells, showing “all the essential hallmarks of a candidate pandemic virus,” the researchers wrote. The news sounds disturbing, especially in light of the current coronavirus pandemic, but doctors say you shouldn’t freak out just yet. Here’s what you need to know about G4.
What is the G4 virus, exactly?
The G4 virus is a newly discovered strain of the H1N1 flu virus. “It’s basically a virus that’s found in pigs but has combined the swine flu virus with the H1N1 virus that circulates in humans,” explains Amesh A. Adalja, M.D., senior scholar at the Johns Hopkins Center for Health Security. “It has the potential to become a human virus.”
Dr. Adalja says experts don’t always know when swine flu viruses will emerge in humans. “They can cause sporadic infections in fairs, but most are dead ends,” he says. “But, in 2009, we saw swine flu take off.”
It’s not shocking that researchers found the G4 virus, says William Schaffner, M.D., an infectious disease specialist and professor at the Vanderbilt University School of Medicine. “We now have the capacity to look for variant influenza viruses and investigate them to the extent we never had before,” he says. “The more you look, the more you’ll find.”
Researchers “periodically” find “candidate viruses” that are recombinant, meaning they combine with a virus from another organism, like between pigs and humans or humans and birds, Dr. Schaffner says. “Periodically, one of these viruses pick up human genes that permit them to circulate freely among the population. Then we get a new pandemic,” he says, noting that it happens every 10 to 15 years.
Can the G4 virus infect humans?
It can. The researchers in the PNAS study discovered that the G4 virus has already infected some people in China, noting that more than 10% of swine workers on pig farms and 4.4% of people in the general population in the Hebei and Shandong provinces, which have big pig populations, tested positive for the virus between 2016 and 2018.
But the fact the virus has shown up in humans for years and hasn’t caused a global pandemic is a good sign, Dr. Schaffner says. “It hasn’t taken off yet. There must be something about it that it doesn’t have explosive potential or that it hasn’t done so yet,” he says. “Whether this can be transmitted the way flu usually does from person to person does not yet appear to be the case. However, there is enough there so that these investigators have sent up an alert.”
How worried about the G4 virus should you be?
There’s “always a concern” that the virus could start spreading efficiently between people, Dr. Adalja says. “It already has some viral characteristics coming from human flu viruses, so there’s reason to keep this one on the radar,” he says.
Dr. Schaffner says the G4 virus’ ability to attach to human cells is “bothersome, because that’s usually a characteristic that permits the virus to transmit readily from person to person.”
Also, keep this in mind: Even though the G4 virus has H1N1 genes and the seasonal flu vaccine helps protect against H1N1, Dr. Adalja says it’s unlikely that the vaccine will help provide immunity against G4, if it were to start heavily circulating in people.
Overall, Dr. Adalja says that the general public “shouldn’t be concerned” about the G4 virus yet, but it’s something that scientists are tracking.
“It’s something researchers have got to keep their eye on, but we don’t know yet whether this virus is going to get nasty on us,” Dr. Schaffner adds. “There are others that have come up in the past that have had pandemic potential, but haven’t spread readily. That’s where this is at the moment.”
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