The Biden administration’s push to make Covid-19 booster shots available to most fully vaccinated adults has been stymied for now by a Food and Drug Administration advisory panel’s recommendation that Pfizer boosters be made available only to those 65 and over and those at high risk of severe Covid.
However, the roiling debate over whether the shots are needed more broadly remains unsettled.
The panel of experts on Friday overwhelmingly voted not to recommend boosters for those over 16 after a tense, daylong debate that put divisions within the agency and the administration on public display.
The vote was a blow to President Biden, strengthening criticism of his effort to enhance the immunity of already vaccinated Americans at a time when most residents of poor nations have not even had first doses. The F.D.A. and the Centers for Disease Control and Prevention authorized third shots for some immunocompromised individuals more than a month ago, on the ground that the additional dose would simply lift their protection to the level other people achieve with two shots.
Some F.D.A. experts said that the data from Pfizer and elsewhere still seemed to show that two shots protected against severe disease or hospitalization for months afterward, and that there was not enough evidence that a third shot would stem the spread of infection. Some also criticized a lack of data that an additional injection would be safe for younger people.
The panel’s final recommendations left some room for the White House to argue that the core of its booster strategy remained intact. Depending on how “at high risk” is defined, tens of millions of Americans could conceivably be deemed eligible for additional shots of the Pfizer vaccine. And a small but growing number of people have stopped waiting for federal authorization and are finding ways to receive booster shots.
Before the panel met on Friday, the Centers for Disease Control and Prevention released data indicating that, for some people, the level of protection against Covid hospitalizations afforded by the Pfizer-BioNTech vaccine dropped significantly four months after full inoculation.
Sept. 18, 2021, 7:21 p.m. ET
The C.D.C. study supported some others that suggest the Pfizer vaccine may offer less protection from hospitalization over time. The available data is far from unanimous, though so far it suggests that only older adults will need boosters. Participants in the C.D.C. study skewed older and it was unclear if the same waning of vaccine effectiveness happened among younger vaccinated people.
Other studies have shown that Pfizer’s effectiveness against hospitalization has remained above 90 percent, despite the rapid spread of the Delta variant and the passage of time. Pfizer has said that data from Israel suggests a falling effectiveness against severe disease, though it appears that Israel and the United States define “severe disease” differently.
The debate is playing out as the Delta variant continues ravaging less-vaccinated areas of the country. New coronavirus cases and Covid hospitalizations across the United States have started to show signs of decline, although they remain far higher than they were earlier in the summer. And the average number of daily deaths has been increasing since early July, from this year’s low of 175 to nearly 2,000 by the end of this week, according to a New York Times database. About one in every 500 Americans has died from the disease.
The pace of vaccinations remains relatively sluggish. Providers are administering about 775,000 doses per day on average, according to federal data, a fraction of the April peak but still more than 250,000 higher than the low point in July. About 54 percent of Americans are fully vaccinated, according to a New York Times database, the second lowest proportion among the Group of 7 wealthy nations — but Japan’s now aggressive vaccination campaign is likely to leave the United States last among the G-7 shortly.
The F.D.A. has the final word on vaccine approvals, and while it is not obliged to follow the advisory committee’s recommendations, it typically does. The agency will likely issue a decision on boosters by early next week.