On March 31, 2021, Pfizer and BioNTech announced that "in a Phase 3 trial in
adolescents 12 to 15 years of age with or without prior evidence of SARS-CoV-2
infection, the Pfizer-BioNTech COVID-19 vaccine BNT162b2 demonstrated
100% efficacy and robust antibody responses, exceeding those recorded earlier
in vaccinated participants aged 16 to 25 years old, and was well tolerated."
These results are from a Phase 3 trial in 2,260 adolescents 12 to 15 years of
age in the United States. In the trial, 18 cases of COVID-19 were observed
in the placebo group (n = 1,129) versus none in the vaccinated group (n = 1,131).