Pfizer and BioNTech said Wednesday that their Covid-19 vaccine prevented symptomatic disease and was well-tolerated in a Phase 3 study of adolescents ages 12 to 15. The companies say they will submit the data to the FDA as an amendment to the vaccine’s emergency use authorization, and will also submit the results to other regulators around the world. … The companies also said that the vaccine was well-tolerated, with symptoms similar in the 12 year-old to 15 year-old age group as among those aged 16 to 25. The vaccine is authorized in the U.S. for people aged 16 and older.