The Pfizer-BioNTech COVID-19 vaccine was 100% effective in teens ages 12 to 15, the company said Wednesday, providing hope there will be an option for people under age 16 before the next school year.

Pfizer said it found 18 cases within a placebo group but none in the vaccine arm of a trial involving over 2,200 participants. The antibody response also exceeded levels detected in an earlier trial of people ages 16 to 25.

The company said it will amend its emergency-use filing with the Food and Drug Administration in the coming weeks, as they target a rollout before fall.

“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,” Pfizer CEO Albert Bourla said.

Currently, the Pfizer vaccine is approved for use in the U.S. by those 16 and older. Versions from Moderna and Johnson & Johnson are approved for those 18 and older.

Children and adolescents tend to see better outcomes from coronavirus infections than older persons, though the lack of vaccine options leaves a big gap in the country’s pursuit of herd immunity to wrangle the virus outright — beyond just stiff-arming severe disease in older and medically vulnerable people.

Pfizer and BioNTech said they will be working with regulators beyond the U.S. to approve their shots for younger people.