More than 10 months after U.S. adults started receiving coronavirus vaccines, the nation’s younger children moved significantly closer to getting a shot of protection when advisers to the Food and Drug Administration on Tuesday endorsed the Pfizer-BioNTech vaccine.

The advisory committee found that the benefits of the shot outweighed the risks of a rare cardiac side effect and voted 17 to 0 with one abstention to back the vaccine for children 5 to 11 years old, a group that numbers 28 million. While the advice is not binding, the agency is all but certain to grant emergency authorization for the vaccine, perhaps as soon as this week.

A pediatric vaccine has been eagerly anticipated by many parents who want to ensure their children’s safety at school and holiday gatherings. Experts say the immunizations will represent a milestone in a pandemic that has killed more than 737,000 people in the United States.

“To me, it seems that it is a hard decision but a clear one,” said Patrick S. Moore, a University of Pittsburgh microbiologist and committee member. He noted that 94 children between 5 and 11 have died of covid-19, and “all have names. All of them had mothers.”

The Centers for Disease Control and Prevention’s outside immunization advisers are scheduled to meet Nov. 2 to recommend how to use the vaccine. Once CDC Director Rochelle Walensky signs off, providers would be able to give the two-dose regimen as soon as the first week of November.

The authorization of the first pediatric vaccine would open the latest chapter in an extended effort to immunize the population of the United States against the coronavirus — an endeavor that began last December with the distribution of the Pfizer-BioNTech vaccine for certain adults.

Pfizer and its German partner BioNTech are expected to have initial data for children 2 to 4 years old and for those 6 months to 2 years old late this year or early next year.

The vote came after a vigorous debate over the safety of the vaccine, which has been linked to rare heart-related complications, such as myocarditis, an inflammation of the heart muscle. Some members of the committee questioned whether the shot should be used for all children, or just those at higher risk because of underlying medical conditions. Several expressed discomfort about making the decision without more information, while others said the data on safety and efficacy were strong enough to move ahead.

So, I guess for me it’s always nerve-racking, I think, when you’re asked to make a decision for millions of children based on studies of only a few thousand children,” said Paul A. Offit, a vaccine expert at Children’s Hospital of Philadelphia. “I think I know enough to move forward with the yes vote, but, you know, it’s always never when you know everything, it’s when do you know enough?”

Amanda Cohn, a vaccine expert at the CDC and member of the panel, argued the data clearly showed the vaccine “will prevent deaths, will prevent ICU admissions and will prevent significant long-term adverse outcomes in children.

But Michael G. Kurilla, an infectious-diseases expert at the National Institutes of Health who abstained from voting, was more skeptical.

“There are high-risk individuals, and I think they do need to be attended to. We do need to provide a vaccine for them,” Kurilla said. “But for many others, one dose or no dose, even. If they’ve had prior covid infection, they may not need anything more.”

Other panel members also said they would have preferred to make more specific recommendations to emphasize that high-risk children with underlying conditions or suppressed immune systems should get the vaccine, but healthy children may hold off.

James E.K. Hildreth Sr., chief executive of Meharry Medical College, said he hoped the CDC’s vaccine advisers, in their meeting next week, would “prioritize the vaccine in some way” for children who face the most risk from the virus. He said he voted to recommend the shot primarily because he wanted “to make sure that the children who really need this vaccine, primarily the Black and Brown children in our country, get the vaccine.”

Arnold Monto, a University of Michigan epidemiologist who is acting chairman of the panel, reminded other committee members that their vote was just the first step toward making the vaccine available. The CDC may be able to craft more clear guidelines for parents of children 5 to 11 years old, he added.

Cody Meissner, a pediatrician at Tufts Medical Center, said he was worried a broad authorization of the vaccine would lead to vaccine mandates at schools. He said he opposes them until more safety data is available.

The Pfizer-BioNTech and Moderna vaccines have been associated with myocarditis and pericarditis, which is an inflammation of the heart lining, after the second dose, particularly in adolescent boys and young men. The problem did not turn up in the Pfizer-BioNTech pediatric clinical trial, which experts say was too small to detect such a rare complication.

Much of the debate focused on the FDA’s use of statistical modeling to try to answer the key question for an emergency authorization: Do the vaccine’s benefits outweigh the risks?

Hong Yang, senior adviser at the FDA’s biostatistics office, told the committee the agency estimated how many hospitalizations caused by covid might be prevented by the vaccine compared with how many hospitalizations might occur because of vaccine-related heart complications.

The agency concluded the benefits outweighed the risks in almost all scenarios, except possibly when there are very low levels of viral transmission. Even then, the FDA said, the benefits might exceed the risks because vaccine-related myocarditis cases have tended to be mild, while covid can lead to serious illness and death.

Some panel members suggested, however, that the FDA assumed there would be more covid cases than will actually occur, considering the number of cases is declining. Such an overestimate would inflate the benefits of the vaccine.

But Monto cautioned that scientists have assumed in the past that the pandemic was waning and “been caught flat-footed as the rates again went up. So … thinking that this is going to be the end of the wave permanently is maybe a little overly optimistic.”

William C. Gruber, senior vice president for vaccine clinical research and development at Pfizer, told the panel the vaccine could have salutary effects beyond preventing illness, including allowing more in-person school and reducing the transmission of the virus — an argument that resonated with several panel members.

There were 2,268 children originally in the Pfizer-BioNTech trial, two-thirds of whom received the vaccine with the rest receiving a placebo. After regulators asked the company to increase the trial size, partly to broaden its safety database, the trial was expanded to about 4,500 children.

The companies reported that the trial showed the vaccine is almost 91 percent effective in preventing symptomatic coronavirus, with 16 cases of covid in the placebo group and three in the vaccine group. The regimen for 5- to 11-year-olds is 10 micrograms, one-third the dose for people 12 and older. As with the older group, children would receive the vaccine in two doses three weeks apart.

Throughout Tuesday, health officials stressed that while children are much less likely to become seriously ill from the virus, they are far from unscathed.

Peter Marks, director of the FDA’s Center for Biologics Evaluation and Research, said 1.9 million children 5 to 11 years old have been infected by the coronavirus and more than 8,300 have been hospitalized.

During the part of the meeting devoted to public comment, several people argued that the vaccine was not safe, that authorizing it would lead to mandates and urged the advisers to reject it. Others pressed for the vaccine to be cleared.

“We haven’t taken our daughter to eat inside of a restaurant or to the movies or on a plane since covid began,” said Belinda Macauley, an attorney in Thousand Oaks, Calif., who has an 8-year-old daughter. “My family is enthusiastically in favor of prompt approval and our daughter will get it the first day it’s authorized.”

Nevertheless, some experts predict there won’t be a huge flood of vaccinations anytime soon. Aaron E. Carroll, a pediatrician and chief health officer of Indiana University, said people are overestimating “how many parents will rush out and get their children vaccinated. Many parents will be conservative, they will want to wait.”

While a large proportion of older people are vaccinated, parents of small children tend to be young, with much lower immunization rates, Carroll noted, adding they are unlikely to get their children immunized if they have not been vaccinated themselves. Only about half of adolescents eligible for a vaccine have received it, with the numbers higher among the older adolescents, he said.

Carroll’s concern is backed up by a Kaiser Family Foundation report issued last month. It found that only about one-third of parents who have children 5 to 11 years old say they would vaccinate their children as soon as possible. Another third said they would “wait and see,” while 24 percent said they would “definitely not” get their children vaccinated. Seven percent say they would do so only if required.

Booster shots of the Moderna and Johnson & Johnson vaccines became available for some people last week after federal regulators gave their blessing to the additional doses and declared that people who are eligible for an additional shot could get any booster regardless of which vaccine they originally received.

As the authorization of the pediatric vaccine approaches, the Biden administration and Pfizer-BioNTech have been racing to prepare to distribute the vaccine and reduce the potential for confusion among medical providers administering pediatric and adult doses.

Nicholas W. Warne, Pfizer’s vice president of pharmaceutical research and development, told the FDA advisers the company will package the pediatric vaccine with orange vial caps, orange labels, orange boxes and orange shipping cartons to differentiate it from shots given to adults and adolescents. The higher-dose vaccine for individuals 12 and older comes in a vial with a purple cap.

White House officials have said they have bought enough doses to vaccinate every child in the 5 to 11 age group. They plan to make the specially packaged vaccine available at more than 25,000 pediatricians and doctors offices, hospitals, pharmacies, community health centers, and school- and community-based clinics. They also will conduct a campaign to educate parents more fully about the vaccines.