Scientists gave Russia's Sputnik V vaccine the green light on Tuesday saying it was almost 92% effective in fighting Covid-19 based on peer-reviewed late-stage trial results published in The Lancet international medical journal.
Experts 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," said Ian Jones, professor at the University of Reading, and Polly Roy, professor at the London School of Hygiene & Tropical Medicine.
"But the outcome reported here is clear and the scientific principle of vaccination is demonstrated," the scientists, who were not involved in the study, said in a comment shared by The Lancet.
"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 began in Moscow, 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 viral vectors, administered 21 days apart — was 91.6% effective against symptomatic Covid-19.
Effective in elderly
The number of people vaccinated in Russia has remained low so far.
Authorities have pointed to some early issues with scaling up production while polls have shown low demand among Russians for the vaccine.
Russia has already shared data from its Phase III trial with regulators in several countries and has begun the process of submitting it to the European Medicines Agency (EMA) for approval in the European Union, Dmitriev said.
The data release comes as Europe scrambles to secure enough shots for its 450 million citizens due to production cuts by AstraZeneca and Pfizer.
The US roll-out, meanwhile, has been hampered by the need to store shots in ultra-cold freezers and uneven planning across states.
There were 2,144 volunteers over 60 in the Sputnik V trial and the shot was shown to be 91.8% effective when tested on this older group, with no serious side-effects reported that could be associated with the vaccine, The Lancet summary said.
RDIF's Dimitriev also said the Gamaleya Institute was testing the vaccine against new variants of Covid-19 and the early signs were positive.
The vaccine was also found to be 100% effective against moderate or severe Covid-19, as there were no such cases among the group of 78 participants who were infected and symptomatic at 21 days after the first shot was administered.
Four deaths of participants occurred, but none was considered associated with vaccination, The Lancet said.
"The efficacy looks good, including in the over 60s," said Danny Altmann, a professor of immunology at Imperial College London.
"It's good to have another addition to the global arsenal."