A total of 500 healthy adult volunteers at the age from 18 to 85 years will be randomized into two treatment (vaccination) groups in ratio 3:1 by double-blind design.

Volunteers in group 1 (n=375) will be administered a single dose of the vaccine Ad5-nCoV (5E10vp).

Volunteers in group 2 (n=125): will be administered a single dose of placebo. Vaccine Ad5-nCoV or placebo will be administered intramuscularly into the deltoid muscle of the arm at a single dose of 0.5 mL (1 prefilled syringe).