The Food and Drug Administration on Thursday amended the emergency use authorizations for Moderna and Pfizer-BioNTech COVID-19 vaccines to allow some people with weakened immune systems to get a third dose.
The FDA regulatory change is specific to patients who have not been able to develop an adequate immune response against the virus, even after being fully vaccinated. The hope, experts say, is that the extra dose will provide these patients with the levels of protection seen in people without weakened immune systems.
An estimated 2.7% of adults in the United States are immunocompromised, according to the Centers for Disease Control and Prevention. This includes organ transplant recipients, some cancer patients and people living with HIV.
“Today's action allows doctors to boost immunity in some immunocompromised people who need extra protection against COVID-19. As we have already stated, other fully vaccinated people are adequately protected and do not need an additional dose of COVID-19 vaccine at this time, ”Acting FDA Commissioner Janet said on Thursday. Woodcock.
"This action aims to ensure that our most vulnerable - who may need an extra dose to improve their own biological responses to vaccines - are better protected against COVID-19," CDC director Dr. Rochelle Walensky said more early in the day at a meeting at the White House. Briefing of the Covid response team.
The FDA change, however, does not apply to the general population. Such booster doses would only be given if vaccine protection was shown to fall below a certain threshold - although scientists are still working to determine precisely what that threshold is.
"If the data actually shows that the level of protection has dropped below a critical level," said Dr Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases on Thursday, "it is at this point. by then you are going to hear about the boosters' introduction in the general population.
The immunocompromised, however, "never really had a good response to begin with," he said.
The FDA decision paves the way for the CDC to change its official recommendation for a third dose in this group, which is needed before doctors can begin administering them to their immunocompromised patients.
A group of independent CDC advisers are due to meet on Friday to discuss the FDA's amended emergency use authorization and offer ideas on whether to recommend the agency to make the change, Walensky said. .
Such a vote is only taken after the FDA has taken regulatory action. The CDC is not obligated to accept suggestions from its advisory committees, but generally does.
In July, the same group of CDC advisers urged the federal government to take extra doses for immunocompromised patients.
They “do everything they can, getting vaccinated, getting their close contacts vaccinated. And that is not enough. They are still not protected, ”Dr. Sandra Fryhofer, physician in internal medicine and member of the board of directors of the American Medical Association. of the trustees, said at the July meeting.
Indeed, studies have shown that two injections are often not enough to trigger even a small immune response in immunocompromised patients. But a third dose, research has shown, can, in some cases, provide these patients with additional protection.
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A study, published Wednesday in the New England Journal of Medicine, found that a third dose of Moderna vaccine increased antibody levels in organ transplant recipients.
Dr Dorry Segev, associate vice president for research and professor of surgery at Johns Hopkins University, said that even though patients do not develop detectable antibody levels with the first two doses, that does not mean that injections do not work on some level.
It is likely that those first two injections "are already priming the immune system," he said. “All the immune system needs is additional exposure to the vaccine, additional exposure to the components of the spike protein, and then to develop into an immune response. "
Still, it's still unclear how robust the response would be after that third dose. Not enough people were able to get that extra kick to give researchers a good understanding of the impact.
A study by Segev and his team, published last month in the journal Transplantation, highlighted how vulnerable organ transplant recipients are, even after a full vaccination.
The study, which involved more than 18,000 fully vaccinated organ transplant recipients, found that they were 82 times more likely to get a breakthrough infection and 485 times more likely to have this infection resulting in hospitalization or death. , compared to the general population.
This story first appeared on NBCNews.com.
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