COVID-19 vaccines tested against new virus variants

As the world awaits the full-throttle production and distribution of COVID-19 vaccines, the coronavirus continues to evolve. New variants of SARS-CoV-2 first detected in the UK and South Africa in December are believed to be more contagious, while a variant circulating in Brazil has been linked to reinfection in anecdotal reports.

That the virus is changing is not surprising to scientists. “It was not a question of if but when,” says Tony Moody, an immunologist at the Duke Human Vaccine Institute. Now scientists are trying to understand whether these variants will affect the effectiveness of vaccines. A series of new studies is providing some clues.

Multiple groups are studying neutralizing antibodies—which prevent a virus from infecting a cell—from the plasma of people who recovered from COVID-19 or who were immunized with a COVID-19 vaccine, to see if these antibodies can protect against the new variants. The studies, posted on bioRxiv and medRxiv, are not yet peer-reviewed, but scientists say they contain a mixture of encouraging and potentially troubling results.

The studies largely focus on the B.1.1.7 variant of the virus, first identified in the UK, and the B.1.351 variant, first identified in South Africa. Scientists at BioNTech and Pfizer found that neutralizing antibodies from people immunized with the Pfizer-BioNTech vaccine were just as good at targeting B.1.1.7 as they were at targeting strains widely circulating in 2020. Moderna found similar results in people immunized with its vaccine.

But Moderna also found that neutralizing antibody levels for B.1.351 in people immunized with its vaccine were one-sixth the level of antibodies for the other widely circulating variants. The South Africanresearchers who first identified the B.1.351 variant also found similar results when studying the convalescent plasma of people who recovered from COVID-19.

Scientists are relieved to see that the vaccines will likely still work against the B.1.1.7 variant, but they find the results for B.1.351 worrisome. “I would expect that the reduced titers seen in B.1.351 could translate into less effectiveness of the vaccine in practice—how much is unclear, but it is of concern,” John Shon, chief technology officer at Serimmune, an immunology research company, tells C&EN in an email.

Moderna says the levels of neutralizing antibodies from its vaccine may still be high enough to protect against the B.1.351 variant. But it also announced plans to see whether a booster shot of its vaccine can help raise neutralizing antibody levels in people who already got their two required shots.

Moderna is making a new version of its vaccine, based on the mutations found in the B.1.351 variant, which it will also test as a booster shot. “They are following the right path,” Moody says. It’s too early to know if COVID-19 vaccines will have to be updated regularly like influenza vaccines, he adds, but Moderna’s announcement is a step in that direction.

“I think we can expect more variants to emerge, and while we may be able to contain the virus by responding to each set of mutations as they happen, we need a longer term more considered approach,” Dennis Burton, an immunologist at Scripps Research’s California campus, tells C&EN in an email. “That approach is rational vaccine design in which we deliberately identify and target those parts of the virus that show little variation.”

Researchers note that even if vaccines are less effective against new variants, a partially effective vaccine is still useful. “There is nothing in the data that makes me think getting the vaccine is a bad idea,” says Moody, who plans on getting his second shot in the first week of February. “Will it be as protective as we want it to be? Maybe not. But having a 95% effective vaccine was pretty remarkable to begin with. There’s nothing here that says, ‘Abandon course.’ ”