Russia’s Sputnik V vaccine was 91.6% effective in preventing people from developing COVID-19, according to peer-reviewed results from its late-stage clinical trial published in The Lancent international medical journal on Tuesday.

Scientists said the Phase III trial results meant the world had another effective weapon to fight the deadly pandemic and justified to some extent Moscow’s decision to roll out the vaccine before final data had been released.

The results, collated by the Gamaleya Institute in Moscow that developed and tested the vaccine, were in line with efficacy data reported at earlier stages of the trial, which has been running in Moscow since September.

“The development of the Sputnik V vaccine has been criticised for unseemly haste, corner cutting, and an absence of transparency,” Professor Ian Jones of the University of Reading and Professor Polly Roy, of the London School of Hygiene & Tropical Medicine, said in a comment shared by The Lancet.

“But the outcome reported here is clear and the scientific principle of vaccination is demonstrated,” said the scientists, who were not involved in the study. “Another vaccine can now join the fight to reduce the incidence of COVID-19.”

The results were based on data from 19,866 volunteers, of whom a quarter received a placebo, the researchers, led by the Gamaleya Institute’s Denis Logunov, said in The Lancet.

Since the trial in Moscow began, there were 16 recorded cases of symptomatic COVID-19 among people who received the vaccine, and 62 among the placebo group, the scientists said.

This showed that a two-dose regimen of the vaccine - two shots based on two different adenovirus vectors, administered 21 days apart - was 91.6% effective against symptomatic COVID-19.

Russia approved the vaccine in August, before the large-scale trial had begun, saying it was the first country to do so for a COVID-19 shot. It named it Sputnik V, in homage to the world’s first satellite, launched by the Soviet Union.

Small numbers of frontline health workers began receiving it soon after and a large-scale roll out started in December, though access was limited to those in specific professions, such as teachers, medical workers and journalists.

In January, the vaccine was offered to all Russians.

Sputnik V has been approved by 15 countries, including Argentina, Hungary, and the United Arab Emirates and this will increase to 25 by the end of next week, the RDIF’s Dmitriev said.

The sovereign wealth fund also said vaccinations using Sputnik V will begin in a dozen countries, including Hungary, Bolivia, the United Arab Emirates, Venezuela and Iran.

However, large shipments of the shot have only been sent so far to Argentina, which has received enough doses to vaccinate about 500,000 people, and Bolivia, which received 20,000 shots.

Production for export will primarily be conducted by RDIF’s manufacturing partners abroad, the fund has said.

On Tuesday, Dmitriev said that production had begun in India and South Korea, and would launch in China this month. Trial doses have also been produced by a manufacturer in Brazil.

Russia is also conducting a small-scale clinical trial of a one-dose version of the vaccine, which developers expect to have an efficacy rate of 73% to 85%.