There is now real evidence that at least one coronavirus variant seems to elude some of the power of Covid-19 vaccines. What, exactly, that means for the pandemic is still being examined. The vaccines may turn out to be less powerful against the variant, but they still appear to protect people from the worst outcomes, like hospitalization or death. The loss in the intended results against the B.1.351 variant in clinical trials suggests to some experts that the immunity the shots deliver may not last as long against that form of the coronavirus. It is indicated that the vaccines won’t be as powerful in combatting B.1.351 transmission, the way scientists hope the shots will be for other versions of the virus.
Experts say the disparate results could serve as a warning flag that the world needs to step up its current vaccination campaigns and expedite efforts to envision what Covid-19 vaccines 2.0 might look like.
“It’s a huge relief to know that the vaccines still seem to protect against hospitalization and deaths,” said Emma Hodcroft, a molecular epidemiologist at the University of Bern. “The No. 1 thing at the moment is to try and reduce in any way the cost that this virus charges us as it spreads through societies. But it’s definitely true the loss in efficacy, it raises some worrying questions.”
Positive results
Questions about vaccines revolve around the bottom line of whether they “work” or not against the different forms of the SARS-CoV-2 coronavirus. However that oversimplifies what clinical trials are measuring, what the vaccines might be able to do, and how much of this is a matter of degrees, rather than a definitive yes-or-no answer.
The trials have generally been investigating whether the vaccines prevent symptomatic cases of Covid-19. But Covid-19 presents across a full spectrum, from asymptomatic infections to fatal ones, which is why some trials also include data specifically focused on the outcomes in which people are most interested: will it prevent severe disease and death.
In a way, the first clinical trial results from Moderna and the Pfizer and BioNTech team, which both showed the respective vaccines were 90% or more protective against symptomatic disease, spoiled us for what we could expect for immunizations still going through trials. The achievements went way beyond what experts had hoped Covid-19 vaccines could attack.
So when Johnson & Johnson reported last week that its vaccine was, on average, 66% efficacious at blocking moderate and severe disease — a figure that ticked up to 72% when just looking at U.S. participants — many researchers sought to remind people that this was a result worth celebrating. The vaccine was 85% effective against severe disease cases no matter the infectious variant, and all the deaths and hospitalizations in the trial occurred among people who got the placebo, not the vaccine.
“People look at 72% and say well that’s not as good as 90%, but the fact is, if you look at serious disease, it was extremely effective in preventing serious disease, including hospitalizations and deaths,” Anthony Fauci, the head of the National Institute of Allergy and Infectious Diseases, told reporters this week.
Average results
Clinical trial data released last week for the J&J shot and another from Novavax showed the vaccines did not fare as well in South Africa, where the B.1.351 variant first emerged. The efficacy of the J&J shot against moderate or worse Covid-19 fell to 57% in South Africa, while Novavax reported its vaccine was 49% effective in South Africa at preventing symptomatic Covid-19.
Some experts said the results indicated the vaccines might be less powerful against the variant B.1.351 in other ways, too.
Clinical trials have not shown whether any of the existing vaccines can slow the spread of any version of SARS-2, but many experts think the shots will offer some help in that arena, whether because they prevent some infections entirely, or because they make people who still contract the virus less contagious for a shorter time, or some combination of factors.
“If everyone is vaccinated, then maybe that’s not a big deal, because you’ve just got a cold going around,” Hodcroft said. “But if you’ve got a partially vaccinated population, that means you still have some susceptible people, where if a vaccinated person passes it on to a non-vaccinated person, they could still be in danger of being hospitalized or dying.”
Negative results
The question of whether the vaccines might lose more of their power against the variant faster than they would against other SARS-2 iterations is also of concern. How long the protection elicited by any of the existing vaccines lasts against any version of the virus, remains questionable. Researchers would need to track vaccinated people and watch when their immunity wanes in order to gain insight.
Novavax and J&J results should serve signal those in the global scientific community — including vaccine makers and regulators — to prepare, in case the B.1.351 variant or some other form of SARS-2 is able to “escape” immune protection in ways the trial data do not yet show. Vaccines appeared to guard against severe disease from B.1.351 during the trial, but it is uncertain whether people will carry that protection for a long period.
What about the Moderna and Pfizer vaccines?
The clinical trials of the two vaccines authorized in the U.S. — the Moderna and Pfizer-BioNTech products — were completed before COVID variants of concern appeared. Consequently, there is no clinical data on how effective the shots are against B.1.351.
Scientists have studied lab experiments showing how well neutralizing antibodies taken from people who’ve been vaccinated fight off the variants. So far, the companies have reported drops in the antibodies’ potency against B.1.351 or select mutations in the variant, but the message from them and other scientists has been that the shots produce such sky-high levels of defense that they can withstand some loss of response without really changing how well they protect people.
But scientists caution that it’s difficult to determine what those lab experiments mean for the real world. The experiments only look at neutralizing antibodies, while the immune response includes other types of antibodies as well as fighters like T cells.
But the drop in neutralizing antibody power in the experiments, combined with the drop in efficacy in the Novavax and J&J trials, leads some experts to think that if the Moderna or Pfizer vaccines were put up against B.1.351 in trials, they might also see declines in efficacy.
What’s next?
Currently, B.1.351 accounts for just a fraction of global Covid-19 infections. But already, researchers are exploring ways to update vaccines to better target it or other variants that appear. Vaccine makers have announced they’re studying strain-specific boosters or next-generation vaccines that could target multiple variants, and regulators have said they’re considering how to approve modified vaccines without requiring the full package of trials that new products have to fulfill.
B.1.351 is not the only variant that researchers worry could evade the immune response. Another variant identified first in Brazil, called P.1 shares some of the same mutations. There is preliminary evidence that both variants can slip past the protection generated after an initial Covid-19 case and reinfect people more easily than other SARS-2 types.
It remains imperative to vaccinate as many people as quickly as possible with the shots that are available, experts stress. If anything, the variants add pressure to pick up the global pace of vaccinations. The shots protect people from Covid-19. And, if they can help drive down and decrease the likelihood that other potentially dangerous variants emerge.
“We need to vaccinate even faster and even more,” Andersen said. “The vaccines are still effective.”
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