The Sputnik V vaccine developed in Russia is 91.6% effective against symptomatic COVID-19, said the paper published in The Lancet as well as the Russian Direct Investment Fund on Tuesday.

According to the experts behind the study, the Phase 3 trials suggest that the two-dose vaccination provides more than 90% efficacy in the patients who show COVID-19 symptoms. The new analysis included about 20,000 volunteers.

Named after the Soviet-era satellite, Sputnik V was approved in Russia for emergency use months prior to results from its final-stage clinical trials were announced.

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

“But the outcome reported here is clear and the scientific principle of vaccination is demonstrated, which means another vaccine can now join the fight to reduce the incidence of COVID-19,” Jones added.

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“In an interim analysis of Phase 3 clinical trial, Sputnik V showed strong efficacy, immunogenicity and safety results. Efficacy of Sputnik V against COVID-19 was reported at 91.6%,” a statement by Russian Direct Investment Fund said.

The authors of the study, however, said that efficacy was only calculated on symptomatic cases and said more research would be needed to examine how it affects asymptomatic infection.

The Russian government has already launched a mass inoculation campaign for citizens aged 18 and older and several countries, including Belarus, Venezuela, Bolivia and Algeria, have registered for Sputnik V vaccine.