As Pfizer and Moderna ramp up their clinical trials in an effort to get COVID shots to children under 12 as soon as possible, it looks like Pfizer may get an emergency use authorization (EUA) by the end of September 2021.

Pfizer chief scientific officer Dr. Phil Dormitzer told NPR that if they get the EUA, the first shots will go to children 5 years and older; they plan to submit data for children under 5 “shortly thereafter.” Interestingly, Pfizer’s study isn’t looking at whether the shots actually keep children from getting sick; rather, the company tests their blood for antibodies.

It will take another two years to see how long the protection lasts, if the antibodies indeed do prevent disease. Pfizer says they’ve determined that giving children one-third of the adult dose is the “optimal” dosage needed to give similar protection to them as what adults get on the full dose.

Moderna said they also are testing dosages for children, and they’re hoping to have enough data to ask for an EUA by the end of 2021.