The director of the Centers for Disease Control and Prevention said Friday that the South African Covid-19 variant, which was just detected in two people in South Carolina, had already reached the point of community spread in the U.S.
"I think one of the concerning things is that we know these two people did not know one another and that they did not travel to South Africa so the presumption is, at this point, that there has been community spread of this strain," the director, Rochelle Walensky, told Savannah Guthrie on NBC's "TODAY" show.
Walensky said sequencing of the virus has been "scaled up" under the new administration, meaning there's more of a chance to catch a new strain.
Because the South African variant was detected on Thursday doesn't mean it just arrived since the U.S. has lagged greatly behind other countries in tracking changes in the virus by sequencing its genetic code.
Moderna announced this week that its vaccine appears to be less effective against the South African variant, although officials said antibodies remained above protective levels. A Pfizer study, which has not been peer-reviewed, found that the Pfizer-BioNTech vaccine is only slightly less effective against the South African strain.
Meanwhile, an experimental coronavirus vaccine developed by the biotech company Novavax is 89.3 percent effective at preventing Covid-19 but only 49.4 percent effective against the South African strain.
"That has always been our concern that when viruses mutate and they develop strains and dominant strains, they usually do so for some advantage to the virus," Walensky said. "That may come in the tune of our vaccines not working as well."
Still, she said, "even a vaccine that has 50-60 percent efficacy is a strong tool in our toolbox to fight this pandemic," noting that scientists are already working on engineering vaccines based on existing ones that "would be more potent against these strains."