Russia says trials have shown that its Sputnik V vaccine is 95% effective against fighting COVID-19.
It said this figure was based on preliminary results from tests on volunteers, 42 days after the first injection of the vaccine.
It comes a day after it was announced the AstraZeneca-Oxford University vaccine was on average 70% efficient.
Pfizer/BioNTech and Moderna say their vaccines are around 95% effective.
"The data on the high efficacy of the Sputnik V vaccine gives us hope that we will soon have a critical tool in the fight against the novel coronavirus pandemic," said Russia's health minister, Mikhail Murashko.