The Food and Drug Administration authorized Pfizer and BioNTech’s Covid-19 booster shots for people 65 and older and other vulnerable Americans, in line with recommendations given Friday by its key vaccine advisory committee.

The FDA’s decision comes after a more than 8-hour agency meeting Friday where a panel of outside experts debated and voted on Pfizer’s application to offer booster shots to the general public. The agency’s Vaccines and Related Biological Products Advisory Committee voted 16-2 against distributing the vaccines to Americans 16 and older, before unanimously embracing an alternate plan to give boosters to older Americans and those at a high risk of suffering from severe illness if they get the virus.

The FDA granted emergency use authorization to administer the shots to older Americans, those with so-called co-morbidities and front-line health workers and others with jobs that place them at a greater risk of exposure to the virus.

“The FDA considered the committee’s input and conducted its own thorough review of the submitted data to reach today’s decision,” Dr. Peter Marks, the agency’s top vaccine regulator, said in a statement. “We will continue to analyze data submitted to the FDA pertaining to the use of booster doses of COVID-19 vaccines and we will make further decisions as appropriate based on the data.” 

The nonbinding decision by the vaccine advisory committee was expected to be a controversial one as the Biden administration has said it wants to begin offering booster shots to the general public as early as this week, pending authorization from U.S. health regulators.

While the agency hasn’t always followed the advice of its committee, it often does. Still, Marks reminded the panel after the votes that federal regulators did not have to accept its recommendation as written.

He asked the group for suggestions on what other populations the FDA should consider for boosters, like front-line health workers and other occupations that face more exposure to Covid. “We are not bound at FDA by your vote, just so you understand that. We can tweak this as need be,” he said.

Some health experts speculated the agency could depart at least a little from the advice of its committee. Some scientists, including at least two at the FDA, had said they weren’t entirely convinced every American who has received the Pfizer vaccine needed extra doses at this time. However, the nation’s top health regulators, including CDC Director Dr. Rochelle Walensky, acting FDA Commissioner Dr. Janet Woodcock and White House chief medical advisor Dr. Anthony Fauci, already endorsed Biden’s booster plan in August.

The vote puts the committee in an “awkward position” as the administration has already announced they would begin distributing boosters this month, Northwell Health chief of infectious disease Dr. Bruce Farber said prior to the panel’s recommendation.

Before the two votes Friday, which came in the late afternoon, some committee members said they were concerned that there wasn’t enough data to make a recommendation, while others argued third shots should be limited to certain groups, such as people over age 60 who are known to be at higher risk of severe disease. Some members raised concerns about the risk of myocarditis in younger people, saying more research is needed.

Phil Krause, an FDA vaccine regulator who is leaving the agency over pressure from the Biden administration to approve the shots, was critical of the findings presented at the meeting, saying much of the data had not been reviewed by the federal agency or peer-reviewed. He said the models used were complex and scientists have to ensure it “is giving you the correct results.”

“That’s part of the difficulty at looking at this kind of data without having the chance for FDA to review it,” he said.

In outlining plans last month to start distributing boosters as early as this week, administration officials cited three CDC studies that showed the vaccines’ protection against Covid diminished over several months. Senior health officials said at the time they worried protection against severe disease, hospitalization and death “could” diminish in the months ahead, especially among those who are at higher risk or were vaccinated during the earlier phases of the vaccination rollout.

Pfizer said In documents made public last week that an observational study in Israel showed a third dose of the Covid vaccine six months after a second shot restores protection from infection to 95%. The data was collected from July 1 through Aug. 30 when the fast-spreading delta variant was surging throughout the country.

In a presentation Friday, Dr. Sharon Elroy-Preiss of Israel’s Health Ministry argued that if officials there had not begun distributing boosters at the end of July, the nation likely would have exceeded its hospital capacity. Health officials began to see a trend, she said, of individuals in their 40s and 50s who were fully vaccinated become critically ill with Covid.

“We didn’t want to wait to see those results and we knew that we needed to vaccinate a larger portion of the population in order to get the numbers down quickly,” she told the committee. Israeli health authorities expected severe cases to average 2,000 by late August, she said. “We were able to dampen that effect and our severe cases are roughly 700 or less and have stayed stable, even though we still have days at 10,000 confirmed cases.”

The FDA OK is not the final go-ahead. The Centers for Disease Control and Prevention’s vaccine advisory committee held the first day of a two-day meeting Wednesday to debate the third shots with a vote on the FDA’s proposal scheduled Thursday afternoon. If they issue a recommendation and it is approved by the CDC, booster shots could begin immediately.