C.D.C. Panel Recommends Third Vaccine Dose for Immunocompromised

WASHINGTON — An independent panel advising the Centers for Disease Control and Prevention on Friday recommended third doses of coronavirus vaccine for certain people with weakened immune systems, giving its support to the Food and Drug Administration’s authorization of the extra shots.

The F.D.A. on Thursday cleared third doses for people with solid organ transplants and others with similarly weakened immune systems, who face a higher risk of severe bouts of Covid-19.

After nearly three hours of presentations and discussion on Friday, the C.D.C. committee, made up of medical experts, voted unanimously to recommend third shots for people in the category who have already received the two-dose vaccines made by Pfizer-BioNTech or Moderna.

While the panel’s guidance is nonbinding, it is followed closely by physicians and public health departments. Dr. Rochelle Walensky, the director of the C.D.C., quickly signed off on the recommendation, calling it “an important step in ensuring everyone, including those most vulnerable to Covid-19, can get as much protection as possible from Covid-19 vaccination.”

About three percent of Americans have weakened immune systems for a variety of reasons, from a history of cancer to the use of certain medications such as steroids.

Dr. Neela D. Goswami, a C.D.C. official, said the group now eligible for third shots could include those with advanced or untreated H.I.V. infections, those who have undergone certain types of stem cell transplants within the past two years and those receiving certain kinds of chemotherapy, among others.

Those slated for treatments that weaken the immune system should get a third dose beforehand, Dr. Goswami said. Everyone eligible for a third shot should wait at least 28 days after their second before getting it, according to the C.D.C.

Dr. Dorry L. Segev, a transplant surgeon at Johns Hopkins University who has researched the impact of third doses in transplant recipients, praised the C.D.C. for putting out a more detailed guidance on who should receive a third shot.

“It is incredibly difficult to come up with clearly delineated criteria for who should be getting” a third shot among those with weakened immune systems, he added.

Dr. Jose U. Scher, a rheumatologist at NYU Langone Health who has studied the effect of vaccines on the immunocompromised, said that the C.D.C. vote — and the guidance from its experts — would help patients who had been agonizing over whether to seek out a third shot. Previously, he said, when people tested themselves for antibodies after vaccination and came up empty, “there were no tools for us to respond to that.”

“We now know that this population was being left behind,” he said.

Immunocompromised people will not need a doctor’s permission or a prescription to get a third shot, C.D.C. officials said. They will need only to attest that they meet the eligibility requirements for an additional dose. Anyone else, including people with chronic medical conditions, like diabetes or asthma, should not be getting third shots at this point, they said.

Dr. Scher predicted that this honor-system approach could be messy. “I don’t know if there’s any way of corroborating someone’s claim” of being immunocompromised, he said. Requiring some kind of proof, such as a doctor’s note, would be a better process, he said.

The updated F.D.A. authorizations do not apply to immunocompromised people who received the single-dose Johnson & Johnson vaccine. The C.D.C. panel did not offer recommendations on additional shots for that group, which is believed to be small. But the lack of guidance from either the F.D.A. or C.D.C. has left that group in limbo.

“We do understand the challenges here, and because of that we will continue to work very diligently to try to have a solution,” Dr. Peter Marks, the F.D.A.’s top vaccine regulator, said at the panel’s meeting. The F.D.A. is waiting on more data that it expects to receive this month, including Johnson & Johnson’s clinical trial data on the safety and efficacy of two doses.

Dr. Kathleen Dooling, a C.D.C. official, said that patients who qualify for a third dose should ideally seek out the vaccine they already received, but that they could take the other two-dose vaccine if necessary.

Presenting studies that supported giving third doses, Dr. Dooling emphasized that immunocompromised people who receive a third dose should still wear a mask, maintain social distancing with people they do not live with, and avoid crowds and poorly ventilated indoor spaces. She said that people with weakened immune systems had also been shown to be at greater risk of breakthrough infection.

But Dr. Dooling said that early studies of how some immunocompromised people responded to third doses made clear that there could be some benefit. One such randomized, placebo-controlled study of more than 100 organ transplant recipients found that patients who received a third shot of Moderna’s vaccine two months after a second dose showed marked increases in antibody levels.

Dr. Dooling also cited observational studies of solid-organ transplant recipients and patients on hemodialysis, which showed that people who had no detectable antibody response to their initial two doses did have one after a third dose.

Studies have also shown that third doses are safe.

The recommendation from the panel, the Advisory Committee on Immunization Practices, comes as health officials grapple with whether people who were vaccinated early in the nation’s inoculation campaign may need booster doses soon, a move that scientists and public health experts argue is not yet supported by data. Officials at the C.D.C. and F.D.A. have been careful to frame the authorization of third doses for people with weakened immune systems as a separate issue.

“Other individuals who are fully vaccinated are adequately protected and do not need an additional dose of Covid-19 vaccine at this time,” Dr. Janet Woodcock, the acting F.D.A. commissioner, said in a statement on Thursday announcing the authorization, adding that the agency was “actively engaged in a science-based, rigorous process with our federal partners” to consider whether booster doses may be needed.

Some are taking matters into their own hands. Just over a million people who received a two-dose vaccine in the United States have already received a third dose, Dr. Dooling told the C.D.C. panel on Friday.