Agency leaders said there was evidence to justify approval only for older people and those with medical conditions. Many others may not be able to get the shots.
The Food and Drug Administration will permit Covid vaccines for adults over 65 and those with certain medical conditions in the fall, according to new regulatory standards detailed on Tuesday by agency officials.
But the F.D.A. may require data from additional clinical trials before approving the vaccines for healthy Americans younger than 65, agency officials wrote in The New England Journal of Medicine.
New doses offer “uncertain” benefit to many Americans under 65 who have previously been vaccinated or have had Covid, Dr. Vinay Prasad, the F.D.A.’s vaccine division chief, and Dr. Martin Makary, the agency’s commissioner, wrote.
Citing low uptake of recent Covid shots, “the American people, along with many health care providers, remain unconvinced” that the shots are needed, the officials said.
During the pandemic, both officials sharply criticized vaccine mandates and other public health measures intended to turn back the coronavirus.
“The F.D.A. will approve vaccines for high-risk persons and, at the same time, demand robust, gold-standard data on persons at low risk,” Dr. Prasad and Dr. Makary wrote.