The negative vote was the latest in a series of setbacks for President Biden’s booster plan since he first announced it a month ago. Mr. Biden said at the time that he wanted most adults who had gotten a second Pfizer or Moderna vaccine at least eight months ago to start receiving booster shots the week of Sept. 20.
But two weeks after his announcement, leaders of the F.D.A. and the C.D.C. told the White House that it would be impossible to authorize booster shots for recipients of the Moderna vaccine that soon. It is now unclear whether extra injections will be offered to Pfizer recipients, and if so, to how many.
In a remarkable public display of internal dissension, two F.D.A. scientists co-authored a medical journal article earlier this week arguing that there was no credible evidence yet in support of booster shots for the general population. Those officials, who are leaving the agency this fall, joined outside experts and other federal health officials who cast doubt at the meeting on whether Pfizer’s request should be approved.
On the other hand, Dr. Peter Marks, their superior and the official who oversees the F.D.A.’s vaccine division, noted that many well-known vaccines require booster shots and urged the committee to consider the importance of not just of preventing severe disease but of curbing the spread of infection.
After the F.D.A. rules on Pfizer’s request, an advisory committee to the C.D.C. will meet to recommend how exactly the extra doses should be used. Earlier public discussions suggest the C.D.C. committee was also leaning toward tailoring booster shots toward the elderly and others particularly vulnerable to worse outcomes from Covid-19, instead of to all those who received their second injection eight months earlier.
Federal officials argue that even if the C.D.C. adopts that approach, the White House’s original plan will still remain largely intact, because nursing home residents and other elderly people, along with health care and emergency workers, were primarily the groups vaccinated first.
The F.D.A. committee’s vote followed hours of presentations by officials from Pfizer, the C.D.C., the Israeli government and independent experts on the complex array of data they have collected up until now about the waning effectiveness of Pfizer and other vaccines over time.