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Tnow here is real proof that at least one variant of coronavirus seems to elude some of the power of Vaccines against covid-19. What exactly this means for the pandemic is still being clarified.
Even though the vaccines are less potent against the variant, they still seem to protect people from worse outcomes, such as hospitalization or death. But the loss of efficacy against the B.1.351 variant in clinical trials has suggested to some experts that the immunity conferred by the injections may not last as long against this form of coronavirus. Or that the vaccines will not be as powerful as a brake on transmission, as scientists hope the vaccines will be for other versions of the virus.
More urgently, experts say, the disparate results serve as a warning indicator that the world needs to step up current vaccination campaigns and accelerate efforts to imagine what Covid-19 2.0 vaccines might look like.
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“It’s a huge relief to know that vaccines always seem to protect against hospitalization and death,” said Emma Hodcroft, molecular epidemiologist at the University of Bern. “The # 1 thing at the moment is to try to reduce in any way the cost that this virus is charging us as it spreads in societies. But it’s really true the loss of efficiency, it raises worrying questions.
Below, STAT presents the good news and the bad news about vaccines and the B.1.351 variant, and what can happen next.
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Good
The key questions about vaccines sometimes come down to whether or not they “work” against the disease. different forms of the SARS-CoV-2 coronavirus. But that oversimplifies what clinical trials measure, what vaccines might be able to do, and how much that’s a matter of degrees, not a yes or no answer.
Trials have generally looked at whether vaccines prevent symptomatic cases of Covid-19. But Covid-19 exhibits a full spectrum, from asymptomatic infections to fatal infections, which is why some trials also include data specifically focused on the outcome people most want to prevent: serious illness and death.
In a way, the first results of the clinical trials from Moderna and the Pfizer and BioNTech team, both of which showed that the respective vaccines were 90% or more protective against symptomatic diseases, spoiled us for this at what we would expect for immunizations still in testing. The achievements go far beyond what experts hoped Covid-19 vaccines could achieve.
So when Johnson & Johnson reported last week that his vaccine was, on average, 66% effective in blocking moderate and severe disease – a figure that rose to 72% just looking at the American participants – many researchers sought to remind people that this result was worth celebrating . The vaccine was 85% effective against severe disease regardless of the infectious variant, and all deaths and hospitalizations in the trial occurred in people who received the placebo, not the vaccine.
“People look at 72% and say it’s not as good as 90%, but the point is, if you look at serious illnesses, it has been extremely effective in preventing serious illnesses, including hospitalizations and deaths. “Anthony Fauci, the head of the National Institute of Allergy and Infectious Diseases, told reporters this week.
The not so good
Simply put, clinical trial data released last week for the J&J shot and another from Novavax showed that vaccines did not perform as well in South Africa, where the B.1.351 variant first appeared and circulated at the highest levels.
The effectiveness of the J&J vaccine against moderate or worse Covid-19 fell to 57% in South Africa, while Novavax reported that its vaccine was 49% effective in South Africa in preventing symptomatic Covid-19. In another trial in the UK, the Novavax shot was almost 90% effective. (Another variant of global radar, B.1.1.7, first appeared in the UK, and although it is more transmissible, so far it does not appear to have such a large impact on vaccines.)
Beyond the drop in protection, some experts said the results indicated that the vaccines might be less potent against B.1.351 in other ways as well.
Clinical trials have not shown whether any of the existing vaccines can slow the spread of an iteration of SARS-2, but many experts believe the pictures will offer help in this area, either because they prevent certain infections completely, or because they make people who still contract the virus less contagious for a shorter period of time, or a combination of factors.
“When you think of vaccines, you think of the direct impacts on the person vaccinated, but you also think of the indirect effects,” like what it can do to spread, said evolutionary biologist Katia Koelle of Emory University.
But several experts told STAT that the results from Novavax and J&J made them question whether the vaccines would have the same potential benefit on transmission against B.1.351 as over other forms. A less potent vaccine, even if it prevents serious illness, may not galvanize the immune system enough to block infection or reduce infectivity as much.
“If everyone is vaccinated, then that might not be a problem, because you just had a cold,” Hodcroft said. “But if you have a partially vaccinated population, that means you still have susceptible people, or if a vaccinated person passes it on to an unvaccinated person, they could still be in danger of being hospitalized or dying.”
The potentially bad
Experts have also raised the question of whether vaccines might lose more of their potency against the variant faster than they would against other iterations of SARS-2. How long does the protection induced by any of the existing vaccines last against any version of the virus remains an open question. Essentially, researchers need to keep track of people who are vaccinated and watch for when their immunity wanes. But a weaker response might start to dissipate faster.
“When we look at four months after vaccination, six months after vaccination, those numbers could be even worse,” said Kristian Andersen, an infectious disease expert at the Scripps Research Institute, of the different levels of efficacy by variant.
Andersen said the Novavax and J&J findings should serve as a rallying cry for the global scientific community – including vaccine makers and regulators – to prepare, in case the B.1.351 variant or a another form of SARS-2 would be able to “escape” the immune system. protection in a way that the test data does not yet show. He said people shouldn’t assume that because the vaccines appeared to protect against serious B.1.351 diseases during the trial, people will wear this protection for a long time.
“If we just sit around and wait until we have all the perfect data, are you showing or not getting people with serious illness?” Does it help control the transmission? All of these things – if we just sit there and wait, and we’re wrong, it’s bad, ”he said.
What about the other vaccines?
Clinical trials of the two vaccines licensed in the United States – the Moderna and Pfizer-BioNTech products – were completed before some of the variants of concern took off, so there is no clinical data on how the vaccines stack up against them. B.1.351.
Instead, scientists studied in lab experiments to what extent neutralizing antibodies taken from vaccinated people repel variants. So far, companies reported decreases in the potency of antibodies 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 high levels of defense that they can withstand some loss of response without really changing their effectiveness. They protect people.
“There is a lot of wiggle room in mRNA vaccines,” Linda-Gail Bekker, deputy director of the Desmond Tutu HIV Center at the University of Cape Town, told reporters this week, referring to the mRNA technology with which the two vaccines are made. With B.1.351, “even if there is a bit of ding there, we would still be in a very good space.”
But scientists warn that it’s difficult to extrapolate what these lab experiments mean to the real world. The experiments focus only on neutralizing antibodies, while the immune response includes other types of antibodies as well as fighters like T cells. With this thinking, it is possible that the true immune response of vaccines is even more robust. against mutations than laboratory data show.
But the decrease in the potency of neutralizing antibodies in the experiments, combined with the decrease in effectiveness in the Novavax and J&J trials, leads some experts to believe that if the Moderna or Pfizer vaccines were put against B.1.351 in the trials, they could also see decreased efficiency.
What must happen now
At present, B.1.351 represents only a fraction of global Covid-19 infections. But already, researchers are exploring ways to update vaccines to better target them or other disturbing variants that are popping up. Vaccine makers have announced they are investigating strain-specific boosters or next-generation vaccines that could target several variants, and regulators have said they plan to give the green light to modified vaccines without requiring the full set of trials that new products must complete.
B.1.351 is not the only variant that the researchers say may elude the immune response. Another variant, called P.1 and first identified in Brazil, shares some of the same mutations. There is preliminary evidence that both variants can evade the protection generated after an initial case of Covid-19 and re-infect people more easily than other types of SARS-2.
But the results of clinical trials do not change the imperative to vaccinate as quickly as possible as many people as possible with the available vaccines, experts say. If anything, they are adding to the pressure to step up the global pace. The shots protect people from Covid-19. And, if they can help reduce cases – what steps communities and individuals are taking to slow the spread of the virus – they will prevent people from getting sick and dying, and reduce the likelihood of other potentially dangerous variants appearing. .
“We need to vaccinate even faster and even more,” Andersen said. “Vaccines are always effective.”
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