Alliance for Pandemic Preparedness

February 2, 2021

Articles Safety and Efficacy of an RAd26 and RAd5 Vector-Based Heterologous Prime-Boost COVID-19 Vaccine: An Interim Analysis of a Randomised Controlled Phase 3 Trial in Russia

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Interim analysis of the randomized, double-blind, placebo-controlled phase 3 trial for the recombinant adenovirus (rAd)-based vaccine Gam-COVID-Vac (Sputnik V) (n=19,866) showed an efficacy of 91.6% (CI: 85.6%-95.2%) by 21 days after the first dose of vaccine (the day of dose 2). 16 of 14,964 (0.1%) people in the vaccine group developed COVID-19 compared to 62 of 4,902 (1.3%) people in the placebo group. Participants were required to be IgG/IgM negative at baseline for enrollment. Rates of disease onset were similar for the vaccine and placebo groups until about 16 to 18 days after the first dose.

The observed vaccine efficacy was > 87% in all age and sex subgroups (60% male), and 91.8% in participants aged >60 years (11% of participants). 98.5% of participants were white, and the entire study was conducted in 25 hospitals and polyclinics in Moscow, Russia. 94% of reported adverse events were grade 1, with 0.3% and 0.4% of vaccine and placebo group experiencing serious adverse events, respectively. 

Logunov et al. (Feb 2, 2021). Articles Safety and Efficacy of an RAd26 and RAd5 Vector-Based Heterologous Prime-Boost COVID-19 Vaccine: An Interim Analysis of a Randomised Controlled Phase 3 Trial in Russia. The Lancet. https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(21)00234-8/fulltext