Kid Vax Progress: Covid Vaccine Trials in Young Children

The Phase 1 trial of the Pfizer mRNA vaccine in young children began in March with 144 participants at four sites across the country. These children are receiving two injections of the vaccine and will undergo blood draws to check for antibodies to the virus. Once a safe dose of the vaccine has been determined for them, further trials will be conducted to determine its effectiveness.


The Phase 2-3 trial will enroll a total of 4,500 children at 40 sites nationwide. The study is placebo-controlled, so some participants will be randomly assigned to receive placebo (normal saline) while others will receive the vaccine.


Six months after the shots, participants who received the placebo will have the opportunity to be inoculated with the actual vaccine. The trial will continue for 18 more months, during which both groups will undergo blood draws to track the strength and duration of their immune response and to see if they are infected with COVID-19.


If safety and immunogenicity is confirmed, and pending authorization or approval from regulators, Pfizer hopes to submit the vaccine for potential Emergency Use Authorization (EUA) to the U.S. Food and Drug Administration (FDA) sometime in the September-October timeframe for children 5 to 11, and soon after for six months to 5.

A Moderna mRNA vaccine trial of similar design with a projected enrollment of 7,050 participants also began in March. Once safe doses are established, the phase 2-3 trial will first focus on children 5-11 years old, with later inclusion of younger children aged 6 months to 5 years. Moderna has not released a projected date for applying for an EUA from the FDA.


Will an approved COVID-19 vaccine be available for younger school-age children before school starts in the fall? “Sometime in the September-October timeframe” means probably not.