The variant that emerged in South Africa is reported in the U.S. for the first time.
Health officials in South Carolina said on Thursday that they had detected two cases of a more contagious variant of the coronavirus that emerged in South Africa. It was the first report of that variant being detected in the United States.
The South Carolina Department of Health and Environmental Control said it had identified one case on Wednesday, and was notified of a second case the same day by the Centers for Disease Control and Prevention. The variant, known as B.1.351, was originally identified in South Africa and has since been found in about 30 countries.
The United States is conducting little of the genomic sequencing necessary to track the spread of new variants that have caused concern. They include B.1.1.7, first found in Britain and since seen in more than 46 countries and 24 U.S. states, and the P.1 variant, first found in Brazil, which officials in the United States reported detecting this week in Minnesota.
While the coronavirus vaccines now in use in the United States, developed by Moderna and Pfizer-BioNTech, appear to be protective against the new variants, they may be somewhat less effective against the one found in South Africa than against the others. The new variants are also believed to spread more readily than other versions of the virus, and the one found in Britain may lead to more severe disease.
The statement from South Carolina’s health department said that the cases involved no known travel to South Africa and no connection between the two patients, both adults, suggesting that the variant is circulating in the community. One patient was in the southern Lowcountry region of the state, and the other in the Pee Dee region in the northeast.
“The arrival of the SARS-CoV-2 variant in our state is an important reminder to all South Carolinians that the fight against this deadly virus is far from over,” Dr. Brannon Traxler, the department’s interim public health director, said in a statement. “While more Covid-19 vaccines are on the way, supplies are still limited. Every one of us must recommit to the fight by recognizing that we are all on the front lines now.”
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.
Mr. 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, President 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.
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 has been found in Botswana, Ghana, Kenya, Zambia and 24 non-African nations, as well as the French island of Mayotte in the Indian Ocean.
“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.