Nation Pfizer-BioNTech COVID-19 vaccine proves safe and effective for kids ages 12 to 15, company study shows March 31, 2021March 31, 2021 Karen Weintraub, USA TODAY Comments Off on Pfizer-BioNTech COVID-19 vaccine proves safe and effective for kids ages 12 to 15, company study shows Vaccination was 100% effective against symptomatic disease in 12- to 15-year-olds, the company-sponsored study of 2,260 adolescents found.