Russia's one-shot COVID vaccine, Sputnik Light, shows 70% effectiveness against the Delta variant of coronavirus three months after injection.
That's according to the Russian Direct Investment Fund, citing the vaccine's developer.
The data was submitted by the developer ahead of a peer review.
The data comes as Russia battles soaring infections and hesitancy about vaccines at home, while struggling to compete with more established vaccines from Pfizer, Moderna, and AstraZeneca.
Countries around the world are deploying or considering administering third doses of Pfizer or Moderna vaccines or booster shots to some of their population, particularly those with weakened immune systems and the elderly.
But there's no consensus among scientists about how broadly they should be used.
RDIF said Sputnik Light as a booster for other vaccines will be almost as effective against the Delta variant as Russia's flagship two-shot Sputnik V vaccine.
The Sputnik V vaccine, widely used in Russia and approved for use in more than 70 countries, is undergoing a review by the World Health Organization and the EMA.