HHealth officials have identified the first cases of Covid-19 in the United States, caused by a form of rapid spread of the coronavirus seen initially 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 on Thursday. This indicates that there was some local spread of the variant after its arrival in the United States. One case was found in the Pee Dee region of South Carolina and one in Lowcountry.
Thursday’s announcement means that three variants of the coronavirus that appear to be more contagious and have emerged in recent months have been documented in the United States. But, in a way, the news did not surprise experts. They had said for weeks that the variant that first appeared in South Africa, called B.1.351, was probably already in the US, but this country’s limited surveillance system for different coronavirus iterations means that the variant probably went unnoticed afterwards imported via traveler and could even be spreading.
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Earlier this week, Minnesota health officials confirmed the first Covid-19 case caused by P.1, a variant first identified in Brazil. There were a few hundred cases in the United States of variant B.1.1.7, which initially appeared in the United Kingdom.
The three variants are believed to be more transmissible than previous forms of the coronavirus and, if left unchecked, can lead to more cases by infecting more people more quickly. The Centers for Disease Control and Prevention estimates that B.1.1.7 may become the dominant form of coronavirus in the United States in March.
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“It is critical that we all continue to do our part by taking small actions that make a big difference,” said Brannon Traxler, interim director of public health in South Carolina, in a statement. “This includes wearing our masks, staying at least two meters away from others, avoiding large crowds, washing your hands, getting tested frequently and, when possible, getting vaccinated. These are the best tools to prevent the spread of the virus, no matter the strain. “
The three variants evolved independently – all viruses mutate and occasionally capture changes that give them a transmission advantage – but it happens to share some of the same mutations.
B.1.351 and P.1 in particular 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 that the variants will be able to reinfect people who had an initial case of Covid-19.
These studies resulted in concerns that existing Covid-19 vaccines – which were designed based on previous iterations of the virus – may not be as effective against the variants.
On Thursday, for example, Novavax said that its experimental Covid-19 vaccine was 90% effective in a trial in the UK, but 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 have a smaller drop in effectiveness, although more studies are underway. With the mRNA vaccines from Pfizer-BioNTech and Moderna, it appears that the injections lose some of their neutralizing potency against some of the mutations seen in P.1 and B.1.351, but the immune response induced by the vaccines is so incredibly potent that the injections can withstand the loss of some of their vigor while still protecting people from falling ill with Covid-19.
On Monday, Moderna said his injection should still be effective against B.1.351, despite the fact that the neutralizing antibodies generated by the vaccine do not recognize the shape of the virus, as well as other forms. Essentially, the injection-induced antibody response should still be sufficient to help people ward off Covid-19. There is a question, however, whether the vaccine’s immune response will last as long against variants as previous viral iterations.
So far, studies investigating the impact of variants on Pfizer and Moderna vaccines have largely focused on neutralizing antibodies, but experts note that injections also stimulate other parts of the immune system – including T cells, B cells and other types of antibodies – providing additional reasons why current vaccines still work widely against variants.
Still, experts believe that the coronavirus may one day catch a certain set of mutations that threaten the overall effectiveness of vaccines, so, they say, vaccine manufacturers and regulators should begin to consider what it will take to update immunizations to better match the circulating forms of SARS-CoV-2, the scientific name of the coronavirus causes Covid-19.
Moderna and Novavax said they are studying reinforcement shots designed specifically against B.1.351.
For now, the most urgent concern about the variants, the experts emphasize, remains their infectious character. The World Health Organization, for example, warned on Thursday that B.1.351 was causing an increase in cases as it spread from South Africa to other African nations, with Matshidiso Moeti, the WHO regional director, saying the continent “Is at a crossroads. “
Cases in the United States remain very high, but are dropping from peaks earlier this month. If any of the variants takes off, the country could see yet another peak. It will also be necessary for a larger portion of the population to be immune to the virus to slow the spread of more contagious variants, adding even more pressure to the US vaccination campaign.
Last week, scientists in the UK reported that the variant first seen there, B.1.1.7, may also be more deadly than other forms of the virus, although they are still analyzing national data.
Generally, experts really fear a virus that is more transmissible than one that is correspondingly more lethal; more infectious variants can lead to more deaths in general, even if they are no longer lethal just because they result in many more cases.
But with B.1.1.7, “unfortunately, it looks like the virus can be both,” said John Edmunds of the London School of Hygiene & Tropical Medicine.
This story has been updated with details from Novavax clinical trials.