A key Centers for Disease Control and Prevention advisory group unanimously voted Thursday to recommend distributing Pfizer and BioNTech‘s Covid-19 booster shots to older Americans, nursing home residents and other vulnerable Americans, clearing the way for the agency to give the final OK as early as this evening.

The agency’s Advisory Committee on Immunization Practices specifically endorsed giving third Pfizer shots to people 65 and older in the first of four votes. Third shots were also suggested by the panel for those 50-64 years old with pre-existing conditions.

The panel will also vote on whether to recommend the shots for adults who are more frequently exposed to the virus – possibly including people in nursing homes and prisons, teachers, front-line health employees and other essential workers.

In December and January, the elderly were the first to receive the shots.

The vote is seen as mostly a win for President Joe Biden, whose administration has said it wants to give booster shots to all eligible Americans 16 and older as early as this week. Although the CDC panel recommendation didn’t provide the Biden administration with everything they wanted, it will ensure that booster shots are still available for millions of Americans.

The endorsement comes a day after the Food and Drug Administration granted emergency use authorization to administer third Pfizer shots to many Americans six months after they complete their first two doses. While the CDC’s panel’s recommendation isn’t binding, Director Dr. Rochelle Walensky is expected to accept the panel’s endorsement shortly.

Walensky spoke to the committee on Thursday, before the vote. She thanked them for their efforts and laid out the stakes.

She stated that although the data is not complete, they collectively form a picture and are all we need to decide about next steps in this pandemic.

Some committee members expressed concern that boosters being widely distributed could hinder efforts to provide vaccines to unvaccinated people or reduce their confidence about the effectiveness of the vaccines. Others were frustrated that only Pfizer recipients would be eligible to get the shots, leaving out millions of Americans who got the Moderna and Johnson & Johnson vaccines.

After a two-day meeting in which CDC advisors listened carefully to many presentations about data supporting wide distribution of booster shot, the vote was taken at the close of the second day. One presentation by a Pfizer executive showed data that indicated that a third shot is safe and can increase antibody levels.

One presentation on Thursday was given by Dr. Sara Oliver, a CDC official. She presented observations from Israel where officials inoculated the country’s citizens earlier than many countries. They also began giving third shots to its citizens in July.

One FDA official has criticised the Israel data, pointing out that observational studies are not subject to formal clinical trials and don’t meet FDA standards.

Oliver stated that “We can draw on the experiences of Israel to improve our understanding of safety boosters.” Oliver added that only one patient has been reported with myocarditis, a rare condition affecting the heart. This is despite the fact that the country administered nearly three million doses.

Kathleen Dooling from the CDC stated that data suggests that a third dose might reduce the chance of serious illness among older people and patients with comorbidities. She said that myocarditis could be a risk. However, this is rare and usually occurs in younger men.

She added that the third dose of Pfizer BioNTech Covid-19 vaccine has a similar reactionogenicity to the first dose.

After the Biden administration revealed its plan to make boosters available widely, it has been controversial in scientific circles.

In a paper published days before an FDA advisory meeting last week, 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. Two FDA officials at the top and several scientists from The World Health Organization argued that widespread distribution of booster shots to the public was inappropriate in this instance.

In outlining plans last month to start distributing boosters as early as this week, Biden administration officials cited three CDC studies that showed the vaccines’ protection against Covid diminished over several months. According to senior health officials, they were concerned that protection against death, severe illness, and hospitalization could decrease in the coming months, particularly among people who have been inoculated in the early phases of the vaccine rollout.

This story is in its early stages. Keep checking back for more updates.