Russia has announced new data for its COVID-19 vaccine Sputnik V, saying in a statement that the vaccine is 91.4% effective on day 28 after the first dose.
The new, expanded analysis follows an announcement made earlier this month in which Russia claimed that Sputnik V was over 90% effective.
The vaccine, developed by the Gamaleya Institute, consists of two strains of adenoviruses, which usually cause the common cold and are used as ‘vectors’ to carry the gene for the SARS-CoV-2 spike protein.
The initial analysis from the first 16,000 participants to receive both shots of the vaccine candidate was conducted after 20 individuals in the trial contracted COVID-19.
The updated analysis, however, evaluated the vaccine’s efficacy after 39 cases in total were observed in the trial – eight of which occurred in the vaccinated group compared to 31 in the placebo arm.
The efficacy evaluation was conducted among participants 28 days after receiving the first dose, and seven days after the second dose, with the analysis demonstrating a 91.4% efficacy rate.
In addition, the preliminary data on participants conducted at 42 days – 21 days after the second dose – indicates an efficacy rate ‘above 95%’, the Russian Direct Investment Fund (RDIF) added in a statement.
The trial will continue to evaluate Sputnik V in up to 40,000 participants, with the next interim analysis due after 78 COVID-19 cases have been confirmed across the study.
Another adenovirus vaccine is currently being developed by AstraZeneca and Oxford University, which reported a median efficacy rate of 70% earlier this week.
According to the RDIF, its Sputnik V shot is ‘unique’ because it uses two different human adenovirus vectors – in comparison, AZ/Oxford’s vaccine uses the same vector for both doses.
Experts have raised concerns over the pace at which Russia is advancing Sputnik V through both the research, development and regulatory processes.
In particular, Russia’s decision to approve Sputnik V before conducting large-scale phase 3 safety trials in August raised some concerns.
However, when announcing the vaccine’s approval, Russian president Vladimir Putin (pictured) maintained that the vaccine is safe to use, even adding that one of his daughters had been given the vaccine.
The RDIF has already submitted Sputnik V to the World Health Organization (WHO) for emergency use listing, a process that is designed to enable potential vaccines to become available globally at a faster rate.
The vaccine has also been submitted for a WHO prequalification, which indicates the quality, safety and efficacy of a vaccine.