The researchers are concerned that it could mutate further so that it can spread easily from person to person, and trigger a global outbreak.
The study's researchers wrote about the need to control the virus in pigs and monitor those working with the animals.More news: Kings looking into whether Jabari Parker broke coronavirus rule
A bad new strain of influenza is among the top disease threats that experts are watching for, even as the world attempts to bring to an end the current coronavirus pandemic.
That last flu pandemic was the swine flu which started in Mexico in 2009.
"If it does? We know how to make vaccines for influenza viruses".
Prof Kin-Chow Chang told the BBC: "Right now we are distracted with coronavirus and rightly so".
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The virus is a unique blend of three lineages: one similar to strains found in European and Asian birds, the H1N1 strain that caused the 2009 pandemic, and a North American H1N1 that has genes from avian, human, and pig influenza viruses.
Kin-Chow Chang, a professor who works at Nottingham University in the United Kingdom, told the BBC: "Right now we are distracted with coronavirus and rightly so".
A team of Chinese researchers looked at influenza viruses found in pigs from 2011 to 2018 and found a "G4" strain of H1N1 that has "all the essential hallmarks of a candidate pandemic virus", according to the paper, published by the USA journal, Proceedings of the National Academy of Sciences (PNAS). He went on to say that the virus is not an immediate threat but "We should not ignore it".
In theory, a flu pandemic could occur at any time, but they are still rare events.
They said the newly identified virus is a growing problem in pig farms, adding that the widespread circulation of G4 viruses in pigs "inevitably increases their exposure to humans".More news: National Basketball Association players may be allowed to add customized messages to jerseys
"Such infectivity greatly enhances the opportunity for virus adaptation in humans and raises concerns for the possible generation of pandemic viruses", researchers said.