Pfizer COVID booster provides strong immune boost in kids ages 5-11, new study shows – USA TODAY

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Healthy children ages 5 to 11 mount a safe, strong immune response to the Pfizer-BioNTech COVID-19 booster, according to a new study from the companies.

Blood samples from 30 children showed a 36-fold increase in antibodies against the omicron variant after receiving the third shot. In 140 children, a third dose also increased antibodies six-fold against the original strain of the virus.

Because the vaccine is already approved in adults, regulators have allowed immune responses to be used as a metric of effectiveness, instead of actual infections. No new safety issues arose among the 400 children in the booster trial.

The positive results “reinforce the potential function of a third dose of the vaccine in maintaining high levels of protection against the virus in this age group,” according to a Pfizer news release. 

The companies plan shortly to ask the Food and Drug Administration to authorize booster shots for children ages 5-11.

Children ages 5 to 11 receive a 10-microgram dose of the Pfizer-BioNTech vaccine, one-third the dose given to adults. In the study, they were given a third dose six months after the second.

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No vaccines have been authorized for children under 5, with trials still underway. Pfizer-BioNTech found that two vaccine doses, while safe, provided too few antibodies in children ages 2 to 4 and were not likely to be protective. 

The companies are testing the third shot in that age group. The Pfizer-BioNTech vaccine is the only one authorized for use in children.

Pfizer-BioNTech’s studies have included more than 10,000 children under 12 in the United States, Finland, Poland, and Spain.

The Centers for Disease Control and Prevention authorized vaccines for children ages 5 to 11 in early November. There are approximately 28 million American children in that age group and about 10 million have received at least one dose, according to the CDC.

Contact Karen Weintraub at

Health and patient safety coverage at USA TODAY is made possible in part by a grant from the Masimo Foundation for Ethics, Innovation and Competition in Healthcare. The Masimo Foundation does not provide editorial input.