An influential Food and Drug Administration advisory committee on Friday resoundingly rejected a plan to administer booster shots of Pfizer and BioNTech’s Covid-19 vaccine to the general public, saying they needed more data.

But, they could allow older population shots to be administered. The scientists debated the need to give older people a second dose of vaccines after the first vote. There was still the possibility for other votes.

In light of the FDA’s Vaccines and Related Biological Products Advisory Committee non-binding decision, the Biden administration stated that it would like to offer booster shots to the public next week. However, this is subject to authorization by U.S. regulators. The FDA’s Vaccines and Related Biological Products Advisory Committee has advised the agency many times, even though it sometimes doesn’t. The FDA may make its final decision in just hours. Next week, the Centers for Disease Control and Prevention will hold a meeting of two days to review plans for the distribution of the third shot in the United States.

The committee vote was expected to be a controversial one as some scientists, including two senior FDA officials who were involved in the meeting Friday, have said they aren’t entirely convinced every American who has received the Pfizer vaccine needs extra doses right now.

In a paper published days before the advisory committee meeting, a leading group of scientists said available data showed vaccine protection against severe disease persists, even as the effectiveness against mild disease wanes over time. The Lancet medical journal published Monday arguments by two FDA high-ranking officials as well as multiple World Health Organization scientists arguing that the time is inappropriate to distribute booster shots widely.

In outlining plans last month to start distributing boosters as early as next week, administration officials cited three CDC studies that showed the vaccines’ protection against Covid diminished over several months. At the time, senior officials in health said they were worried that protection against serious disease, death and hospitalization could decrease over the next few months. This was especially true for those at greater risk of getting vaccinated earlier during the vaccine rollout.

Some committee members expressed concern that not enough data was available to recommend a third shot. Others suggested that only certain people, like those over 60, should have the option of vaccinating for severe diseases. Some of the members raised concern over myocarditis risks in younger persons, and said that further research was necessary.

A voting member of Dr. Hayley Gans said that she was shocked by the FDA asking the committee for more evidence. Some data on safety was not sufficient.

Paul Offit, another member of the voting committee, stated that while he supported boosters for older people, he was unable to support third shots for children under 60 because there is more risk of developing myocarditis.

Before the vote, the committee heard several presentations of data that supported the large distribution of booster shot, including one from Israel’s health officials. They began inoculating Israel’s citizens ahead of other nations in July and started offering third shots to them in the latter part of July.

Phil Krause (an FDA vaccine regulator, and co-author on The Lancet paper) was critical of Friday’s findings. He said that many of the data hadn’t been peer-reviewed or reviewed by federal agencies. The models were complicated and science must verify that they are giving the right results.

He said that part of the problem of looking at such data is the lack of FDA review.

Pfizer released documents that were made public Wednesday by FDA. They stated in them that an Israeli observational study showed that a third dose Covid vaccine, six months after the first shot restored protection to 95%. Data were collected between July 1, and August 30, when the rapid-growing delta variant was sweeping the nation.

Sharon Elroy-Preiss from Israel’s Health Ministry presented Friday. She said that, if boosters hadn’t been distributed by July 31, the nation would not have had enough hospital beds. According to her, health officials started to notice a pattern in which people aged 40- and 50 who had received full vaccinations became seriously ill with Covid.

The committee was informed by her that they didn’t want the results to be delayed and decided to vaccine a greater percentage of people to reduce the number of cases. According to her, severe cases in Israel were estimated at 2,000 per month by the Israeli health authorities. We were able reduce that impact and now our severe cases number around 700. This is despite still having 10,000 cases confirmed.

The booster shots are well-tolerated by most people. She cited data showing that there was one myocarditis (a rare condition of the heart that has been associated with mRNA vaccines) among the approximately 2.9 million who were given the additional doses.

According to Dr. Joohee, who is an FDA officer, the side effects of booster vaccines are similar to the ones that occur after the second dose of the vaccine, the FDA Office of Vaccines Research and Review said at the meeting.

Pfizer monitored 289 boosters aged 18-55 years old in its phase three trial. 63.8% experienced fatigue; 48.4% suffered from headaches, and 39.1% had muscle pain. Pfizer’s second Covid dose was studied by FDA. The side effects included fatigue in 61.5%, headaches in 54%, and muscle discomfort among 39% of the patients. One adverse event — swelling of the lymph nodes — occurred in 5.2% of booster recipients but just 0.4% of those who received their first two doses.

Lee explained that most cases of lymphadenopathy were minor to moderate in severity and resolved. One case is ongoing, however.

This story is still in development. Keep checking back for more updates.