The interim assessment of the phase III trial of Sputnik V (heterologous recombinant adenovirus (rAd)-based vaccine, Gam-COVID-Vac) displayed 91·6% efficacy against coronavirus disease (COVID-19). It was found to show high immunogenicity and good tolerability in a large cohort. 

A randomized, double-blind, phase III,placebo-controlled trial was undertaken to explore Sputnik V efficacy and safety.

The study incorporated individuals (age at least 18 years) having negative severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) polymerase chain reaction (PCR) and IgG and IgM tests, no infection in 14 days prior to recruitment, and no other vaccinations in 30 days prior to recruitment. In total, 21,977 participants were randomly allocated to receive vaccine (n=16,501) or placebo (n=5476), with stratification by age group. Overall, 19,866 participants were given two doses of vaccine or placebo and were incorporated in the primary outcome assessment. 

Sputnik V was given (0·5 mL/dose) via the intramuscular route in a prime-boost therapeutic regimen: a 21-day interval between initial dose (rAd26) and 2^nd  dose (rAd5), both the vectors carrying the gene for full-length coronavirus glycoprotein S. The major endpoint was the percentage of individuals with PCR-confirmed coronavirus infection from day 21 after receiving the initial dose.

The major endpoint was evaluated in individuals receiving two doses of vaccine or placebo. The severe side effects were determined in all the individuals receiving at least one dose at the database lock, and rare side effects were examined in all subjects receiving two doses and for whom all the data available were confirmed in the case report form at the database lock.

From 21 days after the initial dose of Sputnik V (the day of the second dose), about 0·1% (16/14964) participants in the Sputnik V arm and 1.3% (62/4902) in the placebo arm were reported to have coronavirus infection. The efficacy of the vaccine was noted to be 91·6%. The most reported side effects were grade 1 (94% 7485/7966 total events).

The proportion of participants in which severe adverse events occurred in the vaccine and placebo group is shown in the below table. None were found to be linked to vaccination, with confirmation from the data monitoring committee. Four deaths were witnessed during the trial, none of which were considered associated with the vaccine.

Sputnik V showed high efficacy, immunogenicity, and a good tolerability profile in coronavirus-infected patients.