WASHINGTON — Millions of Americans who received Moderna’s two-shot COVID-19 vaccine are expected to be eligible soon for booster shots, after a federal advisory panel on Thursday recommended a third dose for older and higher-risk adults as well as certain workers.
The unanimous recommendation from the Food and Drug Administration vaccine panel came a few weeks after federal health officials authorized a booster dose of Pfizer’s vaccine, to be given at least six months after an individual gets a second shot.
Unlike the Pfizer booster, the additional Moderna shots will be half doses, 50 micrograms compared to the 100 micrograms in the first and second Moderna shots that are given four weeks apart. The smaller dose resulted in fewer side effects while still boosting immune-system antibodies, according to company officials.
The FDA panel’s Moderna recommendation is for people who are 65 and older, as well as those between 18 and 64 who are at high risk of developing severe COVID-19 or who live or work in situations that increase their risk. The same population groups are eligible for the Pfizer booster.
As with Pfizer, the Moderna boosters are intended to be given six months after the second shot.
That matching eligibility was by design. Dr. Peter Marks, director of FDA’s Center for Biologics Evaluation and Research, said at the beginning of Thursday’s meeting that he hoped the panel would seek to “harmonize” who is getting boosters across the different vaccines in order to reduce confusion.
The next step for the Moderna booster shot is the granting of emergency authorization by the FDA, and then action by the Centers for Disease Control and Prevention on who should receive the boosters. A CDC panel will meet next week to debate those specifics.
The same FDA panel that made Thursday’s recommendation will meet Friday to consider an additional dose of the one-shot Johnson & Johnson vaccine.
The vaccine panel also will be reviewing data on the potential to mix and match different brands of COVID-19 vaccines. That would give more flexibility to state and local officials overseeing vaccination campaigns and to providers administering shots.
Some who received the J&J shot also have sought approval to receive a follow-up dose of either the Pfizer or Moderna vaccines, which studies have shown to have higher efficacy against infection.
The approval of booster shots was initially bumpy, with some federal vaccine officials frustrated by the Biden administration’s aggressive timeline for approving additional shots. Several longtime FDA officials announced their departure from the agency.
The FDA remains led by an acting commissioner, though that may soon change: The Washington Post and Politico reported Thursday that former Food and Drug Administration commissioner Robert Califf, currently a professor of cardiology at Duke University School of Medicine in North Carolina, is expected to be tapped to head the agency.
The advisory panels weighing the Pfizer shot also expressed unease about the broad categories proposed for boosters, questioning whether health care workers, teachers and others really needed another dose due to potential exposure to the virus at their workplace. The eligibility categories were pared back after a contentious committee hearing, and later expanded in the CDC’s recommendation.