The analysis was based on data from volunteers obtained 42 days after the first dose -- which corresponds with 21 days after the second dose, Gamaleya National Research Centre for Epidemiology and Microbiology of the Russian Health Ministry and Russian Direct Investment Fund (RDIF), said.

And based on data obtained 28 days after administering the first dose - seven days after the second dose, the efficacy of the Sputnik V vaccine was found to be 91.4 per cent. 

"The data demonstrating high efficacy of the Sputnik V vaccine gives us hope that we will soon obtain the most important tool in the fight against the pandemic of the novel coronavirus

infection," Russian Health Minister Mikhail Murashko said in a statement.

According to the protocol of Phase III clinical trials of the Sputnik V vaccine, its interim efficacy is calculated at three statistically significant representative control points -- upon reaching 20, 39 and 78 cases of novel coronavirus infection among volunteers both in the placebo group and in the group that received the vaccine.

The second interim analysis of the Sputnik V vaccine efficacy was carried out on the basis of 39 confirmed cases identified in the placebo group (31 cases) and in the vaccine group (8 cases).

The Russian vaccine uses two different vectors based on the human adenovirus, rather than using one and the same vector for two doses.

The next interim data analysis will be conducted upon reaching the third control point of 78 confirmed coronavirus cases among the study participants.

Final data analysis will be available by the end of Phase 3 clinical trials involving 40,000 volunteers.Drug maker AstraZeneca on Monday said that its Covid-19 vaccine, developed with Oxford University, was up to 90 percent effective, making it one of the major drug companies after Pfizer and Moderna to have reported late-stage data for a potential Covid-19 vaccine.