Pfizer's COVID vaccine is safe and appears effective for children under 5, company says

Pfizer-BioNTech's COVID-19 vaccine appears to be safe and effective for children ages 6 months to 5 years, according to a company study released early Monday.

The study of nearly 1,700 children showed the vaccine was as safe as a placebo and more than 80% protective during the omicron outbreak. No new safety concerns were identified during the trial, the companies said in a news release, and the majority of reported adverse events were mild or moderate.

Pfizer and its partner BioNTech have been testing their COVID-19 vaccine in children under 5 since last year. Company research suggested two shots would not be enough to prevent illness in that age group during the omicron outbreak, so the companies added a third shot to the regimen. 

Effectiveness is still unconfirmed in this age group, awaiting more infections, but only 10 children in the trial developed symptomatic cases as of April 29, the companies said. The trial protocol specified that a formal effectiveness analysis would be done once at least 21 children developed symptomatic cases. 

The vaccine is the same as is given to older children and adults, but the dose for younger children is 3 micrograms, one-tenth the size of the adult dose.

Some parents of younger children have become increasingly frustrated by the lack of a vaccine. A group called "Protect their Future" has called for the Food and Drug Administration to authorize the vaccine for that age group, saying it has long been clear the shots are safe and any effectiveness is better than none. 

Moderna also has developed a vaccine for younger children that is being reviewed by the FDA. That vaccine also appears to be safe but less effective than shots for adults.

In Moderna's study of 6,700 children ages 6 months to under 6, researchers found that children who received two shots of a 25-microgram dose developed similar levels of virus-fighting antibodies as young adults who received two doses of the full-strength 100-microgram vaccine. In the study, which took place during the omicron wave, researchers found the vaccine was 51% effective among children 6 months to under 2 and 37% effective among children 2 to under 6.

The FDA has promised to rapidly review the safety and effectiveness data in younger children and plans an advisory panel meeting as soon as June 8 to discuss authorizing shots in that age group.

Pfizer and BioNTech have not yet provided their complete data to the FDA but expect to within about a week, according to the companies.

“We look forward to soon completing our submissions to regulators globally with the hope of making this vaccine available to younger children as quickly as possible, subject to regulatory authorization,” Pfizer chairman and CEO Albert Bourla said in a prepared statement.

In total, Pfizer-BioNTech has tested its vaccine in more than 10,000 children ages 6 months through 11 years in the United States, Finland, Poland and Spain. Some of the children had been infected with the SARS-CoV-2 virus before enrolling in the trial, while others had not.

Children ages 5 to under 12 received a two-dose schedule of 10 micrograms each but have since been authorized for a third dose to combat the more contagious omicron variant.

The majority of American children have been infected with the coronavirus over the past two years; most have had mild symptoms or none at all. But since the pandemic began, data from the Centers for Disease Control and Prevention shows that more than 125,000 minors have been hospitalized with COVID-19 and 1,521 have died, including 477 children under 5.

Karen Weintraub can be reached at

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