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The US Food and Drug Administration is using a controversial strategy to evaluate the next generation of COVID-19 boosters.
The approach is sparking debate as the agency works to make new and improved reminders available in September, hopefully to help prevent serious illness and save lives in the fall and winter.
For the first time, the FDA plans to base its decision on whether to allow new recalls on studies involving mice rather than humans.
“For the FDA to rely on mouse data is just weird, in my opinion,” says John Moore, an immunologist at Weill Cornell Medicine in New York. “The mouse data will in no way be predictive of what you would see in humans.”
But others defend the approach, arguing that the country has had enough experience with vaccines at this point to be sure the vaccines are safe and that there is not enough time to wait for data from the vaccines. human studies.
“We have 500 people a day dying from coronavirus right now. Unfortunately, those numbers could very well increase in the fall and winter. The question is, ‘Can we do something better?'” says the dr. Ofer Levy, a pediatric and infectious disease researcher at Harvard Medical School who also advises the FDA. “And I think the answer is, ‘We can, by implementing this approach.'”
The UK has just approved a new recall
The United Kingdom just approved a new recall which targets both the original strain of the virus and the original omicron variant, called BA.1 – a so-called bivalent vaccine.
But the The FDA rejected the BA.1 bivalent boosters last spring. Instead, the FDA told the vaccine companies that make the mRNA vaccines, Moderna and Pfizer and BioNTech, to develop bivalent vaccines that target dominant omicron subvariants — BA.4 and BA.5 — in the hope that they will provide stronger and more durable protection.
This is why the FDA decided to use a new, simplified strategy for testing new boosters. The agency asks companies to initially submit test results on mice only. Regulators will use these results, along with human neutralizing antibody data from the BA.1 bivalent booster studies, to decide whether to allow boosters.
Companies will continue to collect more data from human studies; these results will probably not be available before the end of October or the beginning of November.
But the big concern is that the boosters may not perform as well as the mouse data might suggest. Mouse experiments are notoriously unreliable.
And with the government tell people not to buy the old boosters now and rejecting the first bivalent vaccines, the FDA really needs strong evidence that BA.4/5 boosters are in fact better, critics say.
“We need to make sure we have strong immunogenicity data in people to show you have a significantly higher neutralizing antibody response against BA.4, BA.5,” says Dr. Paul Offit from the University of Pennsylvania, which also advises the FDA. “I think anything less than that is not acceptable.”
Some also worry that the approach will further erode longstanding efforts to persuade people to get boosted.
“I think it would be good to have data on neutralizing antibodies in a small group of humans,” says Dr. Monica Gandhi, infectious disease researcher at the University of California, San Francisco. “Otherwise, the extrapolation can be considered too large.”
But others agree that time constraints mean the country cannot wait for more evidence. The billions of people who have received the Moderna and Pfizer-BioNTech mRNA vaccines show how safe they are, these experts say.
The new booster will be identical to the original vaccines, except that it will contain the genetic coding for two versions of the protein the virus uses to infect cells – the original vaccine protein and the proteins from the BA.4 and BA subvariants. 5 omicron.
And some scientists say health officials know enough about how vaccines work to start manipulating COVID-19 vaccines like flu shots, which are changed every year to try to match all strains that may be circulating. but are not routinely retested each year. .
“We’re going to use all of this data that we’ve learned not just from this vaccine but from decades of viral immunology to say, ‘The way to be nimble is we’re going to do these animal studies “, declares Deepta Bhattacharya, an immunobiologist at the University of Arizona College of Medicine in Tucson. “We really don’t go too far on a branch here.”
The companies are expected to submit their data to the FDA by the end of the month, and the administration hopes to make millions of doses of the new boosters available starting in September.