Pfizer-BioNTech Covid-19 Vaccine for Kids Was Safe and 90.7% Effective, Companies Say

The vaccine was found to be safe and tolerable, the companies said in a document they submitted to the Food and Drug Administration, which the agency posted online Friday morning.

The FDA is expected to post online soon its own written assessment of study data submitted by the companies. In early October, Pfizer and BioNTech asked the FDA to authorize the vaccine for children 5 to 11 years old.

The documents are being posted ahead of a meeting scheduled for Tuesday of a committee of vaccine experts advising the FDA.

The panel, the Vaccines and Related Biological Products Advisory Committee, will meet to review the evidence of the vaccine’s safety and effectiveness in children, and vote to recommend whether the FDA should authorize the use.

If the vote is in favor, FDA authorization could follow within days. And if the Centers for Disease Control and Prevention subsequently signs off, millions of younger children could get a Covid-19 vaccine for the first time.

There are more than 28 million children ages 5 to 11 in the U.S., according to the American Academy of Pediatrics.

Pfizer and BioNTech said in September that their vaccine was generally well-tolerated and induced strong immune responses in a study of nearly 2,270 children 5 to 11. Each child received two doses three weeks apart, and each shot contained one-third of the dosage used for adolescents and adults.

The vaccine induced neutralizing antibody levels in younger children that were comparable to those seen in people ages 16 to 25 who served as a control group in the study, the companies said.

The Pfizer-BioNTech document had new data from the same study showing that the immune responses appeared to protect children from disease. Researchers found that three children who received the vaccine became sick with Covid-19, compared with 16 cases who received a placebo, resulting in 90.7% efficacy, according to the companies.

Researchers didn’t find any cases of heart-inflammation conditions including myocarditis in children in the study. The companies, however, said the study was too small to detect this potential risk.

Health authorities have said there is an increased risk of myocarditis with Covid-19 vaccines from Pfizer and

Moderna Inc.,

particularly in males under 30 years.

Pfizer also has tested the vaccine at an even lower dosage in children as young as six months.

Pfizer’s vaccine was authorized in December 2020 for people 16 years of age and older, an authorization expanded in May to adolescents 12 and older.

Earlier this week, the Biden administration outlined plans to distribute the Pfizer vaccine to children at doctors’ offices, pharmacies and schools if regulators clear the shots.

Moderna and

Johnson & Johnson

have been studying their Covid-19 vaccines in children, but currently their shots are authorized only for people 18 and older.

Write to Peter Loftus at peter.loftus@wsj.com and Jared S. Hopkins at jared.hopkins@wsj.com