UK scientists have been investigating whether rats could infect humans with coronavirus - and whether the disease could mutate in wild rodents before being passed to people.
Researchers say laboratory evidence indicates that while rats and mice appear unable to contract the most common forms of COVID, the N501Y spike protein mutation found in several concerning variants "has an increased affinity" for rodents.
A report issued by the government's Scientific Advisory Group for Emergencies (SAGE) also found the likelihood that a variant of concern (VOC) that has arisen in humans could infect a rodent and then spread among the animals is high.
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But it concluded that the risks of coronavirus adapting in rodents to create a new, worrying strain was low - and that any adaptation to rodent hosts would make it less transmissible among humans.
The report said: "There is a plausible pathway for infection of rodents with new variants of concern from infected humans following contamination of an environment.
"Experimental evidence has shown SARS-CoV-2 with N501Y has increased affinity for lab rodents and there is nothing to suggest the same would not be true for wild rodents.
"While rodents are a possible animal reservoir, the likelihood currently of a VOC emerging as a result of adaptation in rodents is low, and certainly lower than in the human population, as it is expected that adaptation to rodent hosts would reduce the virus' ability to transmit to or between humans."
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