FDA to clear third dose of vaccine for people with weak immune systems



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WASHINGTON – Federal regulators are expected to allow a third injection of the coronavirus vaccine as early as Thursday for some people with weakened immune systems, an effort to better protect them as the highly contagious Delta variant sweeps the country.

The decision to expand emergency use of the Pfizer-BioNTech and Moderna vaccines is aimed at helping patients with immune deficiencies who are considered most likely to benefit from an additional injection. It covers people who have had solid organ transplants and others whose immune systems are also compromised, according to an official familiar with the plan.

Development will give doctors the flexibility to recommend additional injections for these patients. At least 3% of Americans have a weakened immune system for a variety of reasons, ranging from a history of cancer to the use of certain medications such as steroids.

Many scientists argue that the immunocompromised population is too diverse to uniformly recommend additional injections of the coronavirus vaccine. Some may be protected by the standard vaccine dosage, despite their conditions. Others may be poorly protected by vaccines, but unable to benefit from an additional injection.

Studies suggest that patients such as organ transplant recipients are in between – often showing a weak immune response to the standard vaccination schedule, but getting a third shot. A recent randomized, placebo-controlled study conducted by Canadian researchers found that a third dose of Moderna vaccine improved the immune response in people in this group.

Dr Dorry Segev, of the Bloomberg School of Public Health at Johns Hopkins University, said about half of transplant patients did not have an antibody response to the currently authorized vaccine dose. His team studied 30 transplant patients vaccinated but with negative or weakly positive antibody titers, suggesting a poor response of their immune system to the injections. After an additional injection, 14 of them had higher antibody titers.

The Food and Drug Administration’s decision to allow a third injection for organ transplant recipients and those with also compromised immune systems will be reviewed by an advisory committee of the Centers for Disease Control and Prevention, which is due to meet on Friday. . While the FDA’s action is independent of the panel’s recommendation, in practice, many doctors wait to act until the CDC makes a decision.

If the committee votes to approve the shots, as scheduled, the CDC could issue a recommendation the same day. This could give doctors and pharmacists additional guidance on how to proceed.

France has offered additional doses of the vaccine to some people with weak immune responses since April, and Germany and Hungary recently followed suit. After reviewing multiple regulatory avenues, health officials in the Biden administration decided that extending emergency use authorizations for Pfizer and Moderna was the fastest way to reach those who needed it most. . The FDA is also expected to give full approval to Pfizer-BioNTech’s vaccine by early next month, a move that would also give doctors more freedom to prescribe additional doses.

Although the vast majority of Americans who were vaccinated received Pfizer or Moderna injections, it was not immediately clear how immunodeficient people who received Johnson & Johnson injections should proceed.

The FDA decided not to expand emergency use of the single-dose vaccine, at least in part because health officials first wanted to see the safety data from Johnson & Johnson’s clinical trials and the effectiveness of two doses, according to an official. Johnson & Johnson is expected to release the results of its two-dose study this month.

Some officials in the Biden administration question whether vulnerable segments of the general population will need boosters to boost their protection against Covid-19 – a move that a number of scientists and public experts say cannot be justified by current data.

Such a strategy would be based on a different risk-benefit calculation because vaccines have been shown to be extremely effective against serious illnesses or hospitalization of people without immune deficiency. Some ordinary citizens are already researching booster shots on their own, without waiting for an FDA decision or CDC recommendation.

Dr Dan Barouch, a virologist at Beth Israel Deaconess Medical Center in Boston who worked with Johnson & Johnson to develop their vaccine, said the FDA’s decision to make third injections available for some with weakened immune systems made sense . But he said a similar approach could be appealing to doctors and patients: getting a completely different type of vaccine.

Dr Barouch said there was a long and successful history of mixing and matching different vaccine platforms for other viruses. Because of the similarities in how coronavirus vaccines were produced, he said, the mix was particularly appealing, as it could potentially boost and expand his immunity.

There is no data yet to determine whether protection against the virus is enhanced by such an approach, said Dr Barouch. But researchers at the National Institutes of Health have a study underway that should provide answers by early fall.

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