Pfizer has announced positive results in its efforts to make the COVID-19 vaccine available for children ages 5-11. What exactly does this mean for parents and kids? Dr. Tiffany Kimbrough, pediatrician and mother of two kids ages 5 and under, answers questions on Pfizer’s phase 2/3 trial results and when the vaccine might be available for children.

What is a phase 2/3 trial?

Vaccines must go through several stages of testing before they can be made available to the public. Phase 1 tests safety and assesses if the vaccine induces a proper immune response by giving it to healthy volunteers. In Phase 2, the vaccine is given to people with the characteristics similar to those for whom the vaccine is intended — in this case ages 5-11. Phase 3 involves giving the vaccine to thousands of people in the target group to test for safety and efficacy.

How many kids between the ages of 5-11 did the Pfizer COVID-19 trial include?

These phases of the trial included 2,268 children ages 5-11.

Was it the same dose as that being given to people age 12+?

Trial participants were given two doses of the vaccine, 21 days apart. Each dose was 10 micrograms, which is smaller than the 30-microgram doses given to people 12 and older. This smaller dose was selected with careful thought to safety, tolerability and immunogenicity — or ability to cause an immune response — in children in this age group.

The children’s immune responses to these doses were comparable to the responses seen in people ages 12 and older with the larger doses.

Were the side effects in kids similar to those in adults?

Yes. Pfizer confirmed that side effects were similar to those observed in individuals ages 16-25 — generally mild and short-lived. There were no instances of myocarditis, a type of heart inflammation that has been linked to mRNA vaccines. The Pfizer and Moderna vaccines are both mRNA vaccines.

This is the first time results are being released for this age group. More detailed data will be available when it is peer-reviewed and published, which will occur before emergency use authorization (EUA) is granted by the Food and Drug Administration.

What happens next?

Pfizer plans to apply for emergency use authorization by the end of September. It could be just a matter of weeks from the time of submission to when EUA is granted. Meanwhile, studies continue on children ages 6 months to 5 years, with doses of 3 micrograms for each injection in this age group.