A healthcare worker giving a vaccine.

Trial: Pfizer’s COVID-19 vaccine is 100% effective in 12 to 15 year olds

Sandra Levy
Senior Editor
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A Phase 3 trial of Pfizer/BioNTech's COVID-19 vaccine was shown to be 100% effective and well tolerated in youths ages 12 to 15. 

Pfizer/BioNTech plan to submit the data to the Food and Drug Administration as soon as possible for expanded emergency use authorization of the two-dose vaccine, according to a CNN report.

In the trial of 2,260 participants ages 12 to 15 in the United States, the vaccine elicited strong antibody responses one month after the second dose, exceeding those demonstrated in people ages 16 to 25 in previous trials, Pfizer reported. The vaccine is currently authorized in the United States for emergency use in people 16 and older.

Researchers observed 18 Covid-19 cases among the 1,129 participants who were given a placebo, and none among the 1,131 volunteers who got the vaccine. The data has yet to be peer reviewed.

Pfizer/BioNTech said that the side effects seen in the young teens were similar to those seen among 16 to 25-year-olds. Common side effects include pain at the injection site, fatigue and fever. The participants will be monitored for protection and safety for two years after their second dose.

Those comparisons to the older population are important, because researchers are building off of the knowledge they gained in the adult trials.

Researchers can define a number of antibodies that are a correlate of the protection seen in adults, and then look for that level of antibodies in pediatric participants to know that the vaccine is providing protection. That's why the Covid-19 vaccine trials in children and adolescents have generally required fewer volunteers than the adult trials, the report said.

"We share the urgency to expand the authorization of our vaccine to use in younger populations and are encouraged by the clinical trial data from adolescents between the ages of 12 and 15," said Pfizer CEO Albert Bourla. "We plan to submit these data to FDA as a proposed amendment to our Emergency Use Authorization in the coming weeks and to other regulators around the world, with the hope of starting to vaccinate this age group before the start of the next school year."

"We all long for a normal life. This is especially true for our children," said BioNTech CEO Ugur Sahin. "The initial results we have seen in the adolescent studies suggest that children are particularly well protected by vaccination, which is very encouraging given the trends we have seen in recent weeks regarding the spread of the B.1.1.7 UK variant."

Pfizer recently told CNN that the safety demonstrated in this adolescent trial helped the company make the decision to begin testing its vaccine in younger children.

A separate Phase 1/2/3 study of the Pfizer/BioNTech vaccine in children ages 6 months to 11 years launched last week, when the first children ages 5 to 11 received a shot. Pfizer/BioNTech plans to begin dosing 2 to 5-year-olds next week and work its way down to participants ages 6 months to 2 years. The company aims to enroll 4,644 children in the trial and expects results by the end of 2021.