Covid: What we know about effectiveness of vaccines against new variants

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While there is growing evidence that existing Covid vaccines will work against the UK variant, the Brazilian and South African strains are a "cause for concern", the UK's chief scientific advisor said.

Sir Patrick Vallance told a Downing Street briefing on Friday that there are fears among experts the new variants from Brazil and South Africa may be less susceptible to the vaccines.

He explained that both variants have more differences in shape, which might mean they may not be recognised by antibodies.

He said: “We will find out how effective the vaccines are against this.

“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.”

Health Secretary Matt Hancock has said there is evidence the South African coronavirus variant reduces vaccine efficacy by about 50%, according to video obtained by MailOnline.

In what is reportedly a recording of an online webinar with travel agents this week, he said: “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.”

He 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.

Matt Hancock says the South African strain may make the vaccines 50% less effective Credit: Dominic Lipinski/PA

“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.”

Meanwhile, Sir Patrick assured the public that there is growing evidence from multiple sources that the vaccines will work against the UK strain.

He said in the government briefing: “There’s increasing confidence coupled with a very important clinical observation that individuals who have been infected previously and have generated antibodies appear to be equally protected against original virus and new variant.”