Two cases of a new, “more transmissible” COVID-19 variant linked to South Africa have been identified in the UK, the health secretary has said.
Both cases are contacts of people who travelled from South Africa over the last few weeks, Matt Hancock said at a Downing Street news conference.
Those with the new variant, and contacts of them, are quarantining.
There are immediate restrictions on travelling from South Africa. Sky News understands incoming flights from the country will be stopped.
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In addition, people who have been in contact with anyone who has been in South Africa in the last fortnight have been told they must quarantine.
It is thought the South African strain may be behind a record number of people being hospitalised with COVID-19 in that country.
It comes as UK government figures showed 744 more people have died within 28 days of testing positive for COVID-19, the highest number since 29 April.
And there were a further 39,237 lab-confirmed cases of coronavirus, the highest daily figure during the pandemic – although this is partly due to much wider testing.
Dr Susan Hopkins, from Public Health England, said the new variant recently discovered in the UK, and the one found in South Africa, are “very different” and are “different mutations”.
“Both of them look like they’re more transmissible,” she added.
Dr Hopkins told the Number 10 press conference: “We have more evidence on the transmission for the UK variant, because we’ve been studying that with great detail with academic partners.
“We’re still learning about the South African variant. We are pretty confident that the system we have in place will help control the spread.”
Regarding inoculation, Dr Hopkins said the Pfizer vaccine produces a “strong immune response and it’s broad and acts against lots of variation in the virus”, adding that there is “no evidence at the moment that the vaccine will not work”.
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How contagious is the new variant?
Mr Hancock said: “This new variant is highly concerning because it is yet more transmissible and it appears to have mutated further than the new variant that has been discovered in the UK.”
The new strain is “shortly to be analysed at Porton Down”, the health secretary added.
Mr Hancock said ministers are “incredibly grateful to the South African government for the rigour of their science and the openness and the transparency with which they have rightly acted as we did when we discovered a new variant here”.
Analysis: South African variant ‘seems to have a higher viral load’
Thomas Moore, science correspondent
The new South African strain of the virus is a significant worry and the government has moved swiftly to shut it down.
Health authorities in the country believe the 501.V2 variant is more common in younger adults.
It also seems to have a higher viral load and as a result spreads more easily from person to person.
It’s thought it could partly explain the recent surge of infections in South Africa.
Genetic analysis shows that it shares some of the mutations of the new strain already widespread in the UK, but the two viruses have evolved separately.
The health secretary has ordered anyone who has been to South Africa, or been in contact with someone who has, in the last two weeks to self-isolate immediately.
Once again the rapid genetic analysis of strains in the UK has picked up a mutant virus at an early stage – but has it been soon enough?