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Omicron could have jumped into humans from mice, scientists say.
The mysterious origin of the heavily-mutated Covid variant that triggered global panic only a month ago continues to puzzle experts.
But Chinese scientists now say they may have unearthed evidence linking the mutant strain to mice — in its DNA.
Analysis showed the variant carries mutations that make it better at infecting the animal group — which previous research has shown can catch Covid from humans.
And that it has many more mutations than any other mutant strains, which the scientists held up as yet more proof it did not emerge in humans.
This is not the first time experts have raised the prospect that the variant first appeared in rodents before jumping back into humans.
But most scientists agree that Omicron likely emerged after a prolonged infection in an immunocompromised person, such as an HIV patient.
Some scientists argue that Omicron evolved in mice before jumping back into humans (stock picture). Others say, however, that it likely emerged in an immunocompromised patient
In the study, researchers compared the DNA of Omicron to the original Wuhan virus and other variants including Alpha and Delta which sparked last summer's wave.
They found it had a much higher average number of mutations (53.3) than other mutant strains (28.4 to 35.4).
And that its closest relative was the Gamma variant — which emerged in Brazil — although the two split into separate groups in mid-2020.
