An interim analysis of a Phase-3 trial of Russia’s Sputnik V vaccine against COVID-19 shows the vaccine is safe and has 91.6% efficacy.
The 91.6% efficacy was seen 21 days after the first dose. Although the study was not designed to assess the efficacy of a single dose regimen, the researchers observed a possible partial protective effect of a single dose. The results were published in The Lancet .
Storage at 2-8°C, a favourable temperature profile for global distribution, has been approved by Russia’s Health Ministry.
The Phase-3 trial between September 7 and November 24, 2020 in about 20,000 participants carried out in Moscow at 25 sites found the vaccine was safe.
The time-point for the interim analysis was when 78 COVID-19 cases were reported in participants after receiving the second dose.
Out of about 20,000 participants, about 15,000 received the vaccine while over 4,900 got the placebo. The primary outcome was the proportion of participants with COVID-19 from day 21 after receiving the first dose. On day 21 after the first dose, 16 participants in the vaccine arm and 62 in the placebo group were confirmed to have COVID-19. This translates into 91.6% vaccine efficacy.
Serious adverse events were seen in both arms, 45 in the vaccine arm and 23 in the placebo group, but “none were considered associated with vaccination. Four deaths were also reported during the study – three in the vaccine arm and one in the placebo group – but “none of the deaths were considered related to the vaccine”, the paper reports.
The protection was seen in all age groups, including those older than 60 years.
A different approach
The Sputnik V vaccine uses an approach slightly different from the one used by Oxford-AstraZeneca. While AstraZeneca uses the same adenovirus vector to ferry the genetic material into cells, the Sputnik V vaccine uses two different adenovirus vectors – adenovirus 26 (Ad26) for the first dose and adenovirus 5 (Ad5) for the second dose – to carry the SARS-CoV-2 spike protein. Using two varying serotypes of adenovirus,is intended to overcome any pre-existing adenovirus immunity in the population.
