A new strain of influenza with the potential to become a pandemic has been identified in China by scientists.
It recently appeared and is carried by pigs, but it can infect humans, they say.
The researchers are concerned that it could mutate even more so that it can spread easily from person to person and trigger a global outbreak.
While not an immediate problem, they say, it has “all characteristics” of being highly adapted to infect humans and needs to be monitored closely.
As it is new, people may have little or no immunity to the virus.
Scientists write in the Proceedings of the National Academy of Sciences that measures to control the virus in pigs and close monitoring of workers in the swine industry should be implemented quickly.
A new and bad strain of influenza is among the main disease threats that experts are watching for, even as the world tries to end the current coronavirus pandemic.
The last pandemic flu the world encountered – the 2009 swine flu outbreak – was less deadly than initially feared, mainly because many older people had some immunity to it, probably because of its similarity to other flu viruses that circulated years before.
This virus, called A / H1N1pdm09, is now covered by the annual flu vaccine to ensure that people are protected.
The new strain of influenza identified in China is similar to the 2009 swine flu, but with some new changes.
So far, it has not posed much of a threat, but Professor Kin-Chow Chang and colleagues who study him say he is one of them to keep an eye on.
How concerned should we be?
The virus, which the researchers call G4 EA H1N1, can grow and multiply in the cells lining human airways.
They found evidence of recent infection in people working in slaughterhouses and in the pork industry in China when they analyzed data from 2011 to 2018.
Current flu vaccines do not seem to protect against this, although they can be adapted for this if necessary.
Kin-Chow Chang, who works at the University of Nottingham in the UK, told the BBC: “Right now we are distracted by coronavirus and rightly so. But we must not lose sight of potentially dangerous new viruses.”
Although this new virus is not an immediate problem, it says, “We must not ignore it”.
In theory, a flu pandemic can occur at any time, but they are still rare events. Pandemics happen if a new strain appears that can spread easily from person to person.
Although flu viruses are constantly changing – which is why the flu vaccine also needs to change regularly to keep up – they generally don’t become pandemic.
Professor James Wood, head of the Department of Veterinary Medicine at the University of Cambridge, said the work “comes as a salutary reminder” that we are constantly at risk of a new emergence of pathogens and that farm animals, with which humans humans have more contact than wildlife, can act as a source of important pandemic viruses.