Experts advising the Food and Drug Administration are meeting Tuesday to consider endorsing the Covid-19 vaccine from Pfizer Inc. and BioNTech SE for use in young children.

Their positive recommendation would likely soon lead to an expansion of the U.S. vaccination campaign to millions of young children.

The FDA last week said the results...

Experts advising the Food and Drug Administration are meeting Tuesday to consider endorsing the Covid-19 vaccine from Pfizer Inc. and BioNTech SE for use in young children.

Their positive recommendation would likely soon lead to an expansion of the U.S. vaccination campaign to millions of young children.

The FDA last week said the results from the companies’ late-stage study met the criteria for immune responses in children 5 to 11 years. The agency also confirmed data from the companies showing that the shot was found to be safe and 90.7% effective at preventing symptomatic Covid-19 in a study of the youngsters.

The expert panel, called the Vaccines and Related Biological Products Advisory Committee, is reviewing scientific data about the vaccine’s safety and effectiveness in children, and will vote to recommend whether the FDA should authorize the use.

A thumbs-up from the panel could be followed within days by the FDA authorizing use of pediatric shots of the vaccine.

As the FDA nears a decision on authorizing Pfizer’s Covid-19 vaccine for children 5-11 years old, public-health officials and pediatricians are sharing research with families to assure hesitant parents of the shot's safety. Photo: John Locher/Associated Press The Wall Street Journal Interactive Edition

The FDA, which regulates medical products, must clear a vaccine before it can be used outside of testing. After the FDA’s action, the Centers for Disease Control and Prevention, which offers guidance to doctors, pharmacies and vaccination sites, would set the policy for young children to get the shots.

The FDA isn’t required to accept decisions by the panel but generally does. Panel members—who have weighed in before all of the FDA’s significant Covid-19 vaccine decisions—include infectious-disease experts, professors and practicing physicians.

The panel is likely to debate the risk of myocarditis, a heart-inflammation condition, which has been found in a small number of young men and male teenagers who have received messenger RNA vaccines. The Pfizer-BioNTech and Moderna Inc. shots use mRNA technology. U.S. health authorities have said the risk of the heart condition appears highest in young men and male adolescents after their second dose of one of the vaccines.

No cases of myocarditis were found in the children’s study, though it was too small to detect the potential risk, according to Pfizer and BioNTech.

States and healthcare providers are readying for what will be the largest vaccine campaign since initial doses for adults were made available almost a year ago. Clinics are planned at pediatricians’ offices, schools, community-health facilities and pharmacies, say federal and state officials.

A positive recommendation from the FDA panel could open the door for millions of young children to get vaccinated.

Photo: shawn rocco/duke university/Reuters

Children face a relatively low risk of severe disease and death from Covid-19, but more have been hospitalized than earlier in the pandemic and since the highly contagious Delta variant swept across the nation. Doctors and physicians say vaccinating children is important to protect them and people around them.

An FDA green light will expand the vaccine’s availability to about 28 million additional children.

If the vaccine is authorized, the young children would take two shots three weeks apart. Each shot would contain one-third of the dosage used for adolescents and adults.

Many parents are awaiting the vaccines, hoping to protect their children as the school year gets under way and the holiday season approaches. Yet polls also show there are high numbers of parents who are unsure about inoculating their children.

Pfizer and BioNTech asked the FDA this month to authorize the vaccine for young children. The vaccine is fully approved for people 16 years and older and cleared for use in children 12 years and up.

In a study of 2,268 children 5 to 11 years, the vaccine was generally well-tolerated and generated levels of neutralizing antibodies comparable to those seen in subjects who were 16 to 25 years, according to the companies.

Pfizer and BioNTech are the furthest ahead of companies with authorized Covid-19 vaccines in advancing a shot for young children.

Moderna said Monday that its vaccine was generally safe and induced immune responses in children ages 6 to 11 years in a clinical trial. Johnson & Johnson has yet to study whether the vaccine works in young children.

Write to Jared S. Hopkins at jared.hopkins@wsj.com