While researchers in recent weeks have raised concerns about several new variants of the novel coronavirus, they have identified one variant as particularly worrisome—namely, B.1.351—with data suggesting the variant could affect both vaccine efficacy and natural immunity to the coronavirus.

Weekly line: What the new coronavirus variants mean for vaccines, transmission, and more

What are coronavirus variants?

Since the novel coronavirus pandemic's start, researchers have been testing samples of the virus, known as SARS-CoV-2, to detect whether the virus developed any mutations as it spread. In December 2020, British officials announced that scientists had discovered a new, potentially far-more-contagious variant of the novel coronavirus—labeled B 1.1.7—in the United Kingdom. U.K. officials said the variant had mutations that affect how the virus attaches to and infects cells in the body. For example, one mutation called N501Y improves how the spike protein of the virus—which is the part of the virus that infects human cells—attaches to the ACE2 receptor on human cells, meaning the virus is more likely to infect cells successfully.

Public health experts are concerned about B 1.1.7 because recent research suggests it is about 56% more contagious than the unmutated coronavirus, and researchers have now detected the variant in at least 45 countries, including the United States. CDC has warned that the new variant could become the dominant coronavirus variant circulating within the United States by March.

According to public health experts, a more-contagious variant means new cases of the coronavirus could accelerate, meaning hospitalizations and deaths tied to the virus could spike, as well. Thankfully, early research suggests that the United States' two authorized coronavirus vaccines are effective against B.1.1.7, meaning vaccinations—along with adherence to public health measures intended to curb the coronavirus's spread—could help tamper B.1.1.7's effects.

A more concerning variant emerges

But B.1.1.7 isn't the only new coronavirus variant on scientists' radar—and one of those variants is causing even more concern.

Scientists have discovered another new coronavirus variant in South Africa, called B.1.351, that similarly features the N501Y mutation. But B.1.351 also contains an additional mutation called E484K, which occurs on a part of the spike protein that's instrumental in attaching the coronavirus to ACE2 receptors in human cells. Scientists have also identified the E484K in a coronavirus variant circulating in Brazil, and they've detected the B.1.351 variant in at least 23 countries so far (but not the United States).

Researchers have feared that coronavirus variants with the E484K mutation might be less vulnerable to current Covid-19 vaccines. In the past, studies had indicated that viruses with the E484K mutation are not recognized as well by antibodies as other forms, meaning coronavirus variants with the E484K mutation—such as B.1.351—could potentially bypass immune protection.

For instance, in a pre-print paper from researchers at the Fred Hutchinson Cancer Research Center, the researchers wrote that the location of the E484K mutation is "the site of most concern for viral mutations." Overall, the researchers—which tracked how the antibodies in people who had recovered from Covid-19 fared against different variants—found that while there was variability among the samples, some people experienced as much as a 10-fold drop in neutralization against variants with E484K.

Now, new studies focused specifically on B.1.351's mutations are showing similar results.

The studies were published online and haven't yet been peer-reviewed. Their findings are based on laboratory experiments conducted using blood samples from certain patient groups, so the results don't reflect observations of what's occurring in the real world.

But the results are nevertheless concerning, experts say. According to the New York Times, the new studies indicate that the B.1.351 variant is less susceptible both to the antibodies people produce from being infected by the novel coronavirus and by receiving Covid-19 vaccines manufactured by either Pfizer and BioNTech or Moderna, which are the two vaccines currently authorized for use in the United States.

During a recent scientific conference held online, scientists in South Africa who conducted one of the studies said that, in lab tests, serum samples from 21 of 44 patients who'd had Covid-19 failed to destroy engineered viruses with the B.1.351 variant's spike protein. However, the scientists also noted that serum samples from three Covid-19 patients who'd been hospitalized from the disease did destroy the variant. The scientists said those patients had higher levels of neutralizing coronavirus antibodies in their blood than the patients who had mild cases of Covid-19, according to the Times.

Penny Moore, a virologist at the National Institute for Communicable Diseases in South Africa who led that study, said the findings "strongly, strongly suggest that several mutations that we see in the South Africa variant are going to have a significant effect on the sensitivity of that virus to neutralization."

According to Vox, a separate pre-print study that also examined cell culture but relied on the live virus had similar results. Moore told Vox that the findings are "a serious indication we have to look hard at how well vaccines might work."

In the second study—led by Michel Nussenzweig, an immunologist at Rockefeller University in New York—researchers tested serum samples from 14 patients who'd received Moderna's vaccine and six patients who'd received Pfizer's and BioNTech's vaccine against engineered viruses that contained three of the key mutations found in the B.1.351 variant. The researchers identified a small decline in antibody activity against the viruses—which was a significant result, "because it's seen in just about every individual tested," Nussenzweig said. Overall, the researchers said the findings mean that Covid-19 vaccines "may need to be updated periodically to avoid potential loss of clinical efficacy."

What do the findings mean for Covid-19 vaccines?

Despite the findings, Nussenzweig said current Covid-19 vaccines still are likely to prevent severe cases of Covid-19, so people should continue getting the vaccines. "If your goal is to keep people out of the hospital, then this is going to work just fine," he said.

However, current vaccines might not stop people from developing mild cases of Covid-19 or contracting an asymptomatic coronavirus infection, Nussenzweig said. And if those individuals can transmit the virus to others, it could harm those who haven't yet been vaccinated or infected, the Times reports. That's why public health experts are urging people to continue practicing other measures—including physical distancing, frequent hand washing, and mask wearing—to prevent the coronavirus's spread.

The findings also could mean that vaccine manufacturers might have to update their inoculations to address new variants of the novel coronavirus, and that people might have to get vaccinated against Covid-19 regularly, similar to flu vaccines, the Wall Street Journal reports.

Last month, BioNTech CEO Ugur Sahin said that, if the company's vaccine starts to lose its efficacy because of new variants, BioNTech would be able to adjust its vaccine accordingly—and in a timeframe of about six weeks. "[T]he beauty of the messenger mRNA technology [that the BioNTech/Pfizer vaccine uses as a platform] is we can directly start to engineer a vaccine that completely mimics this new mutation and we could manufacture a new vaccine within six weeks," he said.

And for its part, Moderna on Monday said it was developing a "booster shot" for its vaccine after a pre-print study suggested that it seems "less protective" against the variant identified in South Africa, the New York Times reports. Specifically, the company found that while the British variant had no effect on the levels of neutralizing antibodies produced once someone was vaccinated, the South African variant was correlated with a six-fold reduction in those levels. However, Moderna noted, even those reduced levels "remain above levels that are expected to be productive."

According to Moderna, the booster shot would be given roughly one year after someone received the original vaccine. Officials added that they expect to develop the booster shot in slightly less than 42 days, which was how long it took for the company to develop its original vaccine.

As of Thursday, Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases and the chief medical adviser for the Biden administration's Covid-19 response efforts, said federal officials are "following very carefully [B.1.351], which is a little bit more concerning, but nonetheless not something that we don't think we can handle." He added, "There are alternative plans if we ever have to modify the vaccine. That's not something that is a very onerous thing, we can do that given the platforms we have" (Grady, New York Times, 1/25; Achenbach, Washington Post, 1/15; Mandavilli, New York Times, 1/22; Steinhauser, Wall Street Journal, 1/22; Belluz/Irfan, Vox, 1/22; Higgins-Dunn, CNBC, 1/22; Choi, Politico, 1/21).