This Phase 3 study is randomized, double-blind (blinded for the study subject and investigators), placebo-controlled international multicenter study in the parallel assignment of the subjects to assess efficacy, immunogenicity, and safety of the Sputnik-Light vector vaccine in adults in the SARS-СoV-2 infection prophylactic treatment

The subjects will be randomized into two groups in the ratio of 1:3; a control group (1500 subjects receiving placebo) and a study group (4500 subjects receiving the Sputnik-Light vector vaccine against the SARS-СoV-2-induced COVID19 infection).

For the evaluation of immunogenicity, an unbalanced design is adopted of the placebo and vaccinated group at a 1:3 ratio. Subsequently, the number of subjects in Subgroup A tested will be 1076 subjects, distributed as follows: 269 in the placebo group and 807 in the vaccinated group, also randomized into two groups in the ratio of 1:3 who will attend for assessment of immunogenicity compared to baseline.

Each subject will participate in the trial for approximately 6 months after the first dose of the study vaccine/placebo and will have at least three on-site visits, including a screening visit to the study clinical site during the study period and several observation Phone Call/ Teleconsultation visits during the study