The coronavirus variant circulating in South Africa could be resistant to the vaccine, a leading expert has suggested but stressed that it could take just six weeks to develop a new jab if one was needed.
Sir John Bell, regius professor of Medicine at the University of Oxford, said his "gut feeling" was that the vaccines already on stream would be effective against the new UK strain, which was first identified in Kent.
But he added: "I don't know about the South African strain – I think that's a big question mark."
Matt Hancock, the Health Secretary, said on December 23 that two cases of the South African strain had been identified in the UK. The cases and their contacts were quarantined, and the Government placed strict restrictions on travel from South Africa.
Speaking on Jan 4, he said he was "incredibly worried" about the South African variant of coronavirus.
"This is a very, very significant problem," he said.
Speaking to Times Radio on Jan 3, Sir John said he was more concerned about the South African strain than the UK one "by some margin".
"The mutations associated with the South African form are really pretty substantial changes in the structure of the protein," he said, explaining that the strain had mutated in the part of the virus which allows antibodies to stick to it.
Sir John added that although there was no data yet on whether it increases severity, "it's increased the infectiousness, probably by increasing its ability to bind to the human cells".
Asked whether current Covid-19 vaccines would be able to tackle both the UK and South African variants, he said the Oxford University team was currently assessing this and there was still "room to manoeuvre" because the vaccines worked "much better than any of us thought they were going to".
"I think it's unlikely that these mutations will turn off the effects of vaccines entirely – I think they'll still have a residual effect," he said, adding that it was "perfectly possible" to make new vaccines in a matter of weeks if necessary.
"It might take a month, or six weeks, to get a new vaccine, so everybody should stay calm. It's going to be fine," he said. "But we're now in a game of cat and mouse, because these are not the only two variants we're going to see. We're going to see lots of variants."