Health authorities have identified the first U.S. cases of Covid-19 caused by a fast-spreading form of the coronavirus initially seen in South Africa, in two people in South Carolina.
Neither person has a history of travel to countries where the variant has been confirmed, and there is no connection between the two people, South Carolina health officials said Thursday. That indicates there has been some local spread of the variant after it arrived in the United States. One case was found in South Carolina’s Pee Dee region, and one in the Lowcountry.
The announcement Thursday means that three coronavirus variants that appear to be more contagious and have emerged in recent months have all been documented in the United States. But in a way, the news was no surprise to experts. They had for weeks said the variant that first cropped up in South Africa, called B.1.351, was likely already in the U.S., but this country’s limited system of surveillance for different iterations of the coronavirus meant the variant likely went unnoticed once it was imported via a traveler and could have even been spreading.
Earlier this week, Minnesota health officials confirmed the first Covid-19 case caused by P.1, a variant first identified in Brazil. There have been a few hundred U.S. cases of the B.1.1.7 variant, which initially appeared in the United Kingdom.
All three variants are thought to be more transmissible than earlier forms of the coronavirus and, if left unchecked, could lead to more cases overall by infecting more people faster. The Centers for Disease Control and Prevention has estimated that B.1.1.7 could become the dominant form of the coronavirus in the United States by March.
“It’s critical that we all continue to do our part by taking small actions that make a big difference,” Brannon Traxler, South Carolina’s interim public health director, said in a statement. “These include wearing our masks, staying at least six feet apart from others, avoiding large crowds, washing our hands, getting tested often, and when we can, getting vaccinated. These are the best tools for preventing the spread of the virus, no matter the strain.”
The three variants evolved independently — all viruses mutate and occasionally pick up alterations that give them a transmission advantage — but happen to share some of the same mutations.
B.1.351 and P.1 in particular have raised a different set of alarms than B.1.1.7. Studies have shown that mutations that appear in both variants can help the virus partially evade the human immune response, perhaps making it more likely the variants could reinfect people who had an initial case of Covid-19.
Such studies resulted in concerns that existing Covid-19 vaccines — which were designed based on earlier iterations of the virus — might not be as effective against the variants.
On Thursday, for example, Novavax said its experimental Covid-19 vaccine was 90% effective in one trial in the U.K., but that in a separate trial in South Africa, it was 49% effective. Of the cases that occurred in the South Africa trial for which there was sequencing data, 93% were caused by B.1.351.
Other vaccines made in different ways may see less of a drop in efficacy, though more studies are ongoing. With the mRNA vaccines from Pfizer-BioNTech and Moderna, it seems like the shots do lose some of their neutralizing potency against some of the mutations seen in both P.1 and B.1.351, but that the immune response elicited by the vaccines is so overwhelmingly powerful that the shots can withstand a loss of some of their oomph while still protecting people from getting sick with Covid-19.
On Monday, Moderna said its shot should still be effective against B.1.351 despite the fact that the neutralizing antibodies generated by the vaccine do not recognize the form of the virus as well as other forms. Essentially, the antibody response induced by the shot should still be sufficient to help people ward off Covid-19. There is a question, however, of whether the immune response from the vaccines will last as long against the variants as earlier viral iterations.
So far, the studies investigating the impact of variants on the Pfizer and Moderna vaccines have largely focused on neutralizing antibodies, but experts note the shots also rally other parts of the immune system — including T cells, B cells, and other types of antibodies — providing additional reasons that the current vaccines should still broadly work against the variants.
Still, experts do think the coronavirus could one day pick up a certain suite of mutations that does threaten the shots’ overall effectiveness, so, they say, vaccine makers and regulators should start considering what will be required to update the immunizations to better match circulating forms of SARS-CoV-2, the scientific name of the coronavirus causes Covid-19.
Moderna and Novavax have said they are studying booster shots designed specifically against B.1.351.
For now, the most pressing concern about the variants, experts stress, remains their infectiousness. The World Health Organization, for example, warned on Thursday that B.1.351 was driving a surge in cases as it spread out of South Africa into other African nations, with Matshidiso Moeti, the WHO’s regional director, saying the continent “is at a crossroads.”
Cases in the United States remain sky-high, but they are coming down from peaks earlier this month. If any of the variants take off, the country could see yet another spike. It will also take a greater portion of the population to be immune to the virus to slow the spread of more contagious variants, adding even more pressure to the U.S. vaccine campaign.
In the past week, scientists in the U.K. have been reporting that the variant first seen there, B.1.1.7, may also be deadlier than other forms of the virus, though they are still parsing through national data.
Generally, experts actually fear a more transmissible virus more than one that is correspondingly more lethal; more infectious variants could lead to more deaths overall even if they’re not deadlier just because they result in that many more cases.
But with B.1.1.7, “unfortunately, it looks as if this virus might be both,” said John Edmunds of the London School of Hygiene & Tropical Medicine.
This story has been updated with details from Novavax’s clinical trials.