Participants
MAY
Between April 26 and May 23, 2021, of 24 126 volunteers screened, 18 000 were randomized to placebo or vaccine in cohort 1 and 6000 were randomized to placebo or vaccine in cohort 2. A total of 23 959 participants (cohort 1 [n = 17 972] and cohort 2 [n = 5987]) were randomly assigned to receive the vaccine (n = 19 165) or placebo (n = 4794) (