The second of two new coronavirus variants from Brazil is likely to already be in the UK despite the government imposing a travel ban, a leading epidemiologist has warned.
Eight cases of the first variant, which has a small number of mutations, have been identified in the UK.
The second, which has been detected in the Brazilian city of Manaus and in travellers arriving in Japan, has not been detected in the UK so far.
There are concerns that this variant could be more transmissible and reinfect those who have recovered from COVID, although such possibilities remain unproven.
Professor John Edmunds has said he would it “unusual” if the second variant was not present here.
Professor Edmunds, a member of the government’s Scientific Advisory Group for Emergencies (SAGE), told BBC Radio 4’s Today programme: “In terms of the South African one, we had imported cases already by the time we put in additional restrictions for South African travellers.
“For the Brazilian one… I don’t think there is evidence that we’ve imported cases of the Manaus strain, as far as I’m aware at least, but it is likely that we probably have quite honestly.
“We are one of the most connected countries in the world so I would find it unusual if we hadn’t imported some cases into the UK.”
The government banned flights from South America, Portugal and Cape Verde on Thursday after the emergence of the new variants, having previously banned travel from South Africa because of a new coronavirus mutation.
In addition, all quarantine-free travel into the UK will be suspended on Monday in a bid to keep out other variants.
The new policy means arrivals from every destination will need to self-isolate for 10 days, or receive a negative result from a coronavirus test taken at least five days after they enter the UK.
Labour accused the government of “closing the door after the horse has bolted”, saying the announcement was too late to have stopped the arrival of “worrying” strains.
Shadow home secretary Nick Thomas-Symonds told ministers to get a “comprehensive plan and to act in a proper, strategic way, not in the short-term chaotic way we’ve seen over the past twelve months”.
But aviation minister Robert Courts insisted that the new action amounted to “toughening up already tough requirements”.
Professor Andrew Pollard, director of the Oxford Vaccine Group, said there would be lots of new coronavirus variants this year but the current vaccines should protect against the strains circulating in the UK.
He said that new variants were being detected early, and stressed: “If indeed we do need to make new vaccines we will be able to stand those up really quickly.”
More than 3.2 million people have now received a first dose of a coronavirus vaccine in the UK – around double the number compared to last week.
The government has set a target of vaccinating 15 million of the most vulnerable people in the UK by mid-February.