WASHINGTON — Pfizer/BioNTech announced Friday a study that showed smaller doses of its COVID-19 vaccine for children ages 5 to 11 appear safe and are nearly 91 percent effective at preventing symptomatic disease.

Pfizer's study was released ahead of a pivotal Food and Drug Administration (FDA) advisory panel meeting Oct. 26, where regulators will discuss whether to recommend authorizing the vaccine for younger kids.

The FDA will post its own analysis of Pfizer's safety and efficacy data later on Friday. If the panel votes favorably, and the agency accepts the recommendations, the Centers for Disease Control and Prevention will make the ultimate decision on who should get the shots.

FDA determines safety and efficacy, while CDC regulates the actual practice of medicine. If the vaccine is authorized, children could begin getting immunized in early November, with both doses completed in time for Christmas for the earliest ones in line.

The Biden administration has already purchased enough doses for the 28 million children who would be eligible if the vaccine is authorized.

The Pfizer vaccines has gone through several stages of testing before they can be made available to the public. Phase 1 tests safety and assesses if the vaccine induces a proper immune response by giving it to healthy volunteers.

In Phase 2, the vaccine is given to people with the characteristics similar to those for whom the vaccine is intended — in this case ages 5-11. Phase 3 involves giving the vaccine to thousands of people in the target group to test for safety and efficacy.

These phases of the trial included 2,268 children aged 5-11. Trial participants were given two doses of the vaccine, 21 days apart. Each dose was 10 micrograms, which is smaller than the 30-microgram doses given to people 12 and older.

This smaller dose was selected with careful thought to safety, tolerability and immunogenicity — or ability to cause an immune response — in children in this age group. The children’s immune responses to these doses were comparable to the responses seen in people ages 12 and older with the larger doses. — Agencies