evidence: Thirty-two cases of severe disease, as defined by the CDC, were observed in the placebo group versus none in the BNT162b2 vaccinated group, indicating that the vaccine was 100% efficacious in this analysis against severe disease by the CDC definition (95% CI, [88.0,100.0]). Twenty-one severe cases, as defined by the FDA, were observed in the placebo group versus one case in the BNT162b2 vaccinated group, indicating 95.3% efficacy by the FDA definition (95% CI, [71.0, 99.9]). [...] A total of 697 cases of COVID-19 were observed in the United States; 647 cases of COVID-19 were observed in the placebo group versus 50 in the vaccine group, indicating vaccine efficacy of 92.6% (95% CI, [90.1, 94.5]).