Gov. Henry McMaster wrote on Twitter that the announcement was “important information for South Carolinians to have, but it isn’t a reason for panic” and encouraged residents to wear masks and socially distance.
The C.D.C. said in a statement on Thursday that it was aware of South Carolina’s finding and that it would work to increase genomic sequencing across the country to track virus variants. The agency reiterated its warning against travel at this time.
Starting in March, Britain created an intensive program to track the genetic evolution of the coronavirus, and has sequenced more than 200,000 coronavirus genomes so far — nearly two-thirds of all the ones sequenced in the world. That success is probably why it became the first country to identify the B.1.1.7 virus, in December.
President Biden’s coronavirus czar, Jeffrey D. Zients, said on Wednesday that the United States was woefully behind other nations in tracking the variants, and he used the first White House public health briefing to issue a stark warning that Americans will remain vulnerable to the deadly pandemic unless Congress acts.
On Monday, Mr. Biden issued a ban on noncitizens entering the United States if they have been in South Africa within 14 days, because of concern over the variant. It will go into effect on Saturday. American citizens and permanent residents are not affected, officials said. Asked about the timing of the order at a briefing on Thursday, Jen Psaki, the White House press secretary, said that it took some time to work with airlines and regulatory authorities to put restrictions in place.
“We did that as quickly as possible,” she said.
The administration has also extended bans on travel from Brazil and much of Europe, and imposed a new rule requiring proof of a recent negative virus test before travelers can enter the country.
The B.1.351 variant is predominant in South Africa now, and is driving up new case reports to record levels there and across sub-Saharan Africa, the World Health Organization said on Thursday.
“The variant, which was first detected in South Africa, has spread quickly beyond Africa, and so what’s keeping me awake at night right now is that it’s very likely circulating in a number of African countries,” Dr. Matshidiso Moeti, the W.H.O.’s regional director for Africa, said at a briefing.
Marc Santora contributed reporting.