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AUSTIN (KXAN) – Researchers in China have identified a new strain of swine flu that has “pandemic potential.” It has been more than a decade since the swine flu, known as the virus H1N1, last caused a global pandemic. The CDC estimates that the 2009 H1N1 pandemic killed up to 575,000 people globally. The new virus, known as G4 EA H1N1, has several similarities to the 2009 virus, including its origin: pigs.

“They have flu that’s specific to their species, just like we have flu that’s specific to our species, and it occasionally is able to transfer,” says Ben King PhD., a University of Texas professor who teaches classes on zoonotic diseases, viruses that are able to transfer between animals and people. “There’s always a chance that any of the swine flu’s that are out there, of which there are several, could jump into humans.”

Researchers tested swine workers in two Chinese provinces and found that 10% of those they tested had shown signs of having been infected at some point. Pigs were tested between 2011 and 2018. Researchers found multiple H1N1 viruses during that time, but G4 fits all the criteria for causing a potential pandemic.

Comparing swine flu and COVID-19

COVID-19 and swine flu are from two separate families of viruses. According to the CDC, H1N1 is an influenza virus, the type of virus that causes flus. COVID-19 is comes from the 2019 novel coronavirus and causes respiratory illnesses. Symptoms differ between the diseases. Swine flu’s symptoms include chills, body aches and fatigue. COVID-19 causes heavy coughing, shortness of breath and trouble breathing. However, there are common symptoms between the two, including: fever, coughing and a sore throat.

Swine flu shows symptoms within four days. While COVID-19 can take up to two weeks to show symptoms. Both viruses spread through the air, usually through liquid particles that are ejected from a sick person when they cough. COVID-19 does not currently have a vaccine. Researchers believe that older H1N1 vaccines will likely not work on this new strain.

Unlike COVID-19, the new G4 strain has not yet shown itself to have spread person-to-person. Because of this, Dr. King says that we won’t know if this strain of the virus will act the same way previous H1N1 viruses have. “We won’t know until we know,” Dr. King says, “Will the spread look like 2009? We certainly hope not.”

Likelihood of a second pandemic?

Dr. Angela Rasmussen, a virologist with Columbia University, shared in a Twitter thread that a virus must be able to do five things to have pandemic potential. It must be able to get into cells, replicate, make more viruses, transmit to another host and cause diseases. G4 has shown it can do all these things, except for cause diseases, as researchers do not know when the people they tested, who had viral antibodies, had had symptoms if any.

Because researchers cannot prove that the virus caused symptoms, Dr. Rasmussen, in that same Twitter thread, said that this is where the “potential” part of the “potential pandemic” should be emphasized. She says we should keep an eye on this virus and not “freak out.” Instead, “we should prepare for the flu pandemic that will come: maybe this fall, maybe not for another few years, but is inevitable.”