A NEW Covid-like virus has been discovered in a bat - raising fears it could infect humans.
Scientists in the US have warned that the illness could be resistant to current vaccines.
Covid-19 has now been circulating for over two years and millions of Brits have been vaccinated or have some sort of protection from prior infection.
The current Omicron strain has been proven to be milder than others and globally, many are learning to live with the bug.
Study lead author Dr Michael Letko, of Washington State University in the US, said: "Our research further demonstrates that sarbecoviruses are circulating in wildlife outside of Asia - even in places like western Russia where the Khosta-2 virus was found - also pose a threat to global health and ongoing vaccine campaigns against SARS-CoV-2."
The exact origins of the virus are not clear and are currently being investigated by a team at the World Health Organization (WHO).
Khosta-2 was first found in a horseshoe bat two years ago and medics found that this, like Covid, can infect human cells if transmitted from animal to human.
The researchers said that their findings highlight the importance of developing vaccines that cover a broad spectrum of viruses - not just one lineage such as Covid-19.
Most read in Health
He added: "Unfortunately, many of our current vaccines are designed to specific viruses we know infect human cells or those that seem to pose the biggest risk to infect us.
"But that is a list that's everchanging. We need to broaden the design of these vaccines to protect against all sarbecoviruses."
In recent years, hundreds of sarbecoviruses have been found - mainly in bats in Asia.
In most cases, they are not able to infect humans and initially Khosta-1 and Khosta-2 viruses were not a threat.
Dr Letko said: "Genetically, these weird Russian viruses looked like some of the others that had been discovered elsewhere around the world, but because they did not look like SARS-CoV-2, no one thought they were really anything to get too excited about.
"But when we looked at them more, we were really surprised to find they could infect human cells. That changes a little bit of our understanding of these viruses, where they come from and what regions are concerning."
Writing in the journal PLoS Pathogens, medics said Khosta-2 demonstrated "troubling traits".
This is because like Covid-19, it also uses a spike protein to infect human cells.
This happens when it attaches to a receptor protein called ACE2.
Further tests by the team found that antibodies were ineffective against serum from patients who had previously been infected by the Omicron variant of coronavirus.
While it lacks some genes that Covid has, there is the risk it could combine with Omicron, the experts added.
Dr Letko added: "When you see SARS-2 has this ability to spill back from humans and into wildlife.
"Then there are other viruses like Khosta-2 waiting in those animals with these properties we really don't want them to have, it sets up this scenario where you keep rolling the dice until they combine to make a potentially riskier virus."