Doses of the Sputnik V vaccine in Moscow, Russia.
  • Russia's coronavirus vaccine is 91.6% effective, said an interim analysis of phase-3 data published in The Lancet.
  • Russia approved the drug for emergency use in August, before phase 3 trials, and started giving it to the public in December.
  • One expert said the study had some caveats, but that the results seem to endorse Russia's strategy.
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Russia's Sputnik V coronavirus vaccine is 91.6% effective, an interim analysis of its phase 3 data has found, five months after the country approved the vaccine for use and started giving it to people.

The peer-reviewed study was published in The Lancet on Tuesday. Many of the study's authors are affiliated with Russia's ministry of health, according to The Lancet.

Dr. Julian Tang, a consultant virologist at the UK's University of Leicester, said the interim analysis showed the vaccine to be 91.6% effective after two doses.

But he noted that the trial was only conducted on participants who self-reported symptoms and were then tested, meaning the results only include people with Covid-19 symptoms.

"Further research is needed to understand the efficacy of the vaccine on asymptomatic Covid-19, and transmission," Tang said.

He added that the average follow-up with participants took place 48 days after the full dose, so the study doesn't offer evidence for how long the vaccine protection lasts. 

Russia approved the Sputnik V vaccine for emergency use in August 2020, becoming the first country in the world to approve a coronavirus vaccine.

The approval came before the vaccine had undergone phase 3 trials, which are deemed essential to ensuring the safety of a drug and can uncover rarer side effects.

At the time, medical experts suggested that the vaccine production may have been rushed for political reasons, and warned of dangerous side effects.

Tang said that Tuesday's interim results have, to some extent, justified Russia giving the vaccine to people before phase 3 trial results.

"So despite the earlier misgivings about the way this Russian Sputnik V vaccine was rolled out more widely - ahead of sufficient phase 3 trial data - this approach has been justified to some extent now," he said.

He added that while Russia's strategy has been met with criticism, other countries have also made "compromises" when rolling out their vaccines.

He pointed to the UK, where the government decided to delay giving people their second vaccine dose in order to give as many people their first dose as soon as possible, and where it approved the vaccine for 55-year-olds even though few people of that age were included in clinical trials.

"So we should be more careful about being overly critical about other countries' vaccine designs/ programs," he said.

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