LONDON — Britain, painfully aware of the dangers posed by mutations of the coronavirus after a variant fueled a surge in deaths this winter, has sounded a full-scale alarm over the detection of another variant, this one first registered in South Africa.
In one of the largest concerted testing efforts in the country since the outbreak of the pandemic, the British authorities dispatched mobile units and began testing for 80,000 residents living in areas where the variant had been detected. Free home testing kits left in mailboxes, mobile testing teams going door to door, and new screening sites were among the measures instituted across the affected regions.
As of Monday, health officials had identified 105 cases of the variant in Britain, including in London, with 11 of them not linked to international travel.
Britain, a world leader in genomic surveillance, is well placed to find mutations.
The country has submitted nearly half of the genomes held in a global library run by the nonprofit Global Initiative on Sharing All Influenza Data.
That early alarm system is now being put to the test.
Matt Hancock, the British health secretary, said on Monday: “There’s currently no evidence to suggest this variant is any more severe. But we need to come down on it hard, and we will.” He urged residents in the affected areas to stay at home and to get tested. “This is so important so we can break the chains of transmission of this new variant,” he added.
The plan is for researchers to sequence the entire genome of any coronavirus infections found, looking for mutations. About two mutations are fixed in the virus per month, said Ewan Harrison, a director at Covid-19 Genomics UK Consortium, a research group of health agencies and academic institutions. He noted that with more people being infected and receiving vaccines, there would be selective pressures on the virus, causing it to adapt.
“We know these mutations may make the virus more capable of surviving in presences of antibodies from people who already had a Covid infection,” Mr. Harrison noted.
The variant found in South Africa has prompted extra concern after laboratory tests suggested it might be more resistant to some vaccines.
Roy Anderson, a professor of infectious disease epidemiology at Imperial College London, said that because the variant was already circulating in the community, probably more widely than has so far been detected, it would be hard to nip in the bud.
“It will be very challenging, indeed, to stop it,” he said. But, he added, “You’ve got to try something.”
Britain, which is still under lockdown, has not been very successful in tracking the virus in the past. After the pandemic’s first wave last year, Prime Minister Boris Johnson announced a “world beating” contact-tracing program that aimed to help control the virus’s spread, but a New York Times investigation found that the effort was rolled out too quickly, had poorly trained staff, and suffered from technical glitches.
Susan Hopkins, a senior medical adviser at Public Health England, said that British scientists still expected the available vaccines to reduce hospitalizations and death for those infected with the variant. But they might be less effective, she said.
Professor Anderson of Imperial College said that the emergence of variants added to the urgency of developing vaccines that could easily be adapted or that addressed several variants of the virus at once. “There are going to be lots of other types of this virus emerging,” he said. “It is a taste of what’s to come.”