Initially touted as a laboratory error, a hybrid of Omicron and Delta strain called 'Deltacron' may be real.
Health officials in the UK have identified a patient diagnosed with both Delta and Omicron at the same time, according to the UK Health Security Agency's weekly variant surveillance report.
However, the agency noted it is not clear if it was imported or originated in Britain, the Daily Mail reported.
The UKHSA officials also don't know how infectious or severe the newly-evolved virus is or whether it will impact vaccine performance.
A source at the UKHSA insisted officials were "not concerned" by the variant because case numbers are "low", the report said.
The agency has also not revealed how many times it has been spotted.
According to Professor Paul Hunter, an infectious disease expert at the University of East Anglia, it "shouldn't pose too much of a threat" because the UK has huge levels of immunity against the original Delta and Omicron strains.
"So at the moment I'm not overly worried at the moment. If both Delta and Omicron are falling then, in theory, this (variant) should struggle to take off," he was quoted as saying.
Deltacron as first reported from Cyprus last month, but was later dismissed and put down to sample contamination.
Several "recombinant" variants have been detected in the pandemic, but they have not led to any serious outbreaks.
Scientists say it is "rare" for these to occur, but when they do the variant is normally "less fit" than its rivals and easily outcompeted.
Deltacron "will have shared antigens from both Delta and Omicron and we already have high levels of immunity to those", Hunter said.
"So in theory it should not pose too much of a threat. But nobody can predict everything with certainty, but at the moment I am not overly worried," he noted.