Covid vaccines could begin soon for children 5 and up.

Children ages 5 to 11 may be eligible for Covid vaccines by early next month, according to Dr. Anthony Fauci, the nation’s top infectious disease official. He projected a timetable for young Americans to be vaccinated with at least one dose by early November, and to be fully immunized by the holidays.

Food and Drug Administration regulators on Friday released their evaluation of data from the Pfizer-BioNTech submission for emergency authorization of a lower-dose vaccine for young children. An advisory panel to the F.D.A. will consider Pfizer’s application for those ages 5-to-11 on Tuesday. Children 12 and up have been eligible for vaccination since May.

Pfizer’s data “look good as to the efficacy and safety,” Dr. Fauci said on ABC’s news program, “This Week.”

According to Pfizer and BioNTech, the children who were vaccinated as part of the trial, who received doses that were one-third the size of the adult doses, developed robust immune responses after receiving the regimen of two shots three weeks apart. The companies have said the efficacy rate of the vaccine in children reduced the risk of developing a symptomatic infection by 91 percent.

The most common side effects in children were fatigue, headache, muscle pain and chills. According to the F.D.A., the data submitted indicated no cases of myocarditis inflammation of the heart muscle, or pericarditis, inflammation of the outer lining of the heart, rare complications that have been reported among young boys and men receiving the vaccine in other trials and in real-world applications.

Dr. Rochelle Walensky, the director of the Centers for Disease Control and Prevention, was also interviewed about the upcoming decisions on child vaccines on two Sunday news shows, and seemed to promise that decisions would not be delayed. “We know how many parents are interested in getting their children vaccinated, and we intend to work as quickly as you can,” Dr. Walensky said on “Fox News Sunday.”

The last week has produced a lot of regulatory guidance for those who can receive booster or additional doses of Covid vaccines, giving a large segment of the U.S. population access to more protection.

Both Dr. Walensky and Dr. Fauci sought to dispel confusion about booster shots and explain the option of “mixing and matching” initial vaccines and boosters.

Boosters of all three vaccines available in the United States have been authorized. Additional shots of Pfizer and Moderna mRNA vaccines have been approved for people aged 65 and older, those with underlying health conditions and all adults whose living or working conditions place them at high risk of exposure to the virus. Anyone over the age of 18 who received the single-dose Johnson & Johnson vaccine at least two months ago is also eligible for a booster shot.

People can receive a booster shot that is different from the initial vaccine they first received, experts said.

“If you were originally vaccinated with one product, could you and would it be appropriate and safe and effective to get boosted in the third shot for the mRNA and the second shot for J.&.J. by another product?” Dr. Fauci said. “The answer is, it’s perfectly fine.”