This study was conducted on 21977 individuals, 18 years and above at 25 centres in Russia. The participants were randomly assigned to placebo and vaccines by 1:3 ratio. The vaccine vector components for dose 1 and dose 2 are rAd26-S and rAd5-S, respectively. The study reported 87.6% and 91.6% efficacy at 14- and 21-days post-dose 1. The efficacy of the vaccine after dos 2 was found to be 91.1%.