The coronavirus variant first identified in South Africa could reduce the efficacy of vaccines by half, the health secretary has said.
Matt Hancock made the remark during a webinar with business leaders and travel agents on Tuesday.
First reported by Mail Online, a recording of the meeting has also been passed to Sky News.
In it, Mr Hancock tells those on the call: “There is evidence in the public domain, although we are not sure of this data so I wouldn’t say this in public, but that the South African variant reduces by about 50% the vaccine efficacy.”
The health secretary added: “We’re testing that and we’ve got some of the South African variant in Porton Down, and we’re testing it.
“We’ve got a clinical trial in South Africa to check that the AstraZeneca vaccine works.
“Nevertheless, if we vaccinated the population, and then you got in a new variant that evaded the vaccine, then we’d be back to square one.”
Asked about Mr Hancock’s comments at Friday’s Downing Street news conference, the government’s chief scientific adviser said it was too early to know if the South African variant was more resistant to COVID-19 vaccines.
“We will find out how effective the vaccines are against this,” Sir Patrick Vallance said.
“It is the case that both the South African and Brazilian identified variants have more differences in shape which might mean they are recognised differently by antibodies.
“I think it is too early to know the effect that will have on the vaccination in people and it is worth remembering that the response of the vaccine is very, very high antibody levels, so they may overcome some of this.
“We don’t know but there’s obviously a cause for concern.”
Sir Patrick said that according to Public Health England figures, 44 people in the UK have the South African variant, with a maximum estimate of 71 people having it.
He also said there is “no evidence that the South African or Brazilian variants” are more transmissible than what is already in the UK and therefore “they won’t be expected to spread more quickly or take over”.
Prime Minister Boris Johnson told the briefing that another variant, first identified in the UK before Christmas, may be more deadly than the original virus.
“There is some evidence that the new variant may be associated with a higher degree of mortality,” Mr Johnson said.
But he added: “All current evidence continues to show that the current vaccines remain effective against the old coronavirus variant and this new one.”
A Department of Health and Social Care spokesperson said: “The government is closely monitoring any new variants of concern, including those from South Africa and will continue to take all necessary steps to protect the public.”