Pfizer Inc. PFE, 0.19% and German partner BioNTech SE BNTX, 5.14% said Wednesday that a Phase 3 trial of its COVID-19 vaccine in adolescents aged 12 to 15 showed 100% efficacy and robust antibody responses, an even better result than seen in an earlier study of participants 16 to 25 years old. The trial involved 2,260 adolescents in the U.S. “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,” Pfizer Chief Executive Albert Bourla said in a statement. Last week, the companies dosed the first healthy children in a Phase 1/2/3 study to evaluate the vaccine in children 6 months to 11 years old. That trial will look at the vaccine in three age groups: children aged 5 to 11 years, 2 to 5 years, and 6 months to 2 years. The 5- to 11-year-old cohort started dosing last week, and the companies plan to initiate tests in the 2- to 5 year-old cohort next week. Pfizer shares rose 0.8% premarket, while BioNTech was up 3%.