MOSCOW, Oct 13 — Russia’s one-shot Sputnik Light vaccine shows 70 per cent effectiveness against the Delta variant of coronavirus three months after injection, the Russian Direct Investment Fund (RDIF) said today, citing the vaccine’s developer.

The data was submitted by the developer, the Gamaleya Institute, to medical website medRxiv ahead of a peer review and based on 28,000 participants who received a dose of Sputnik Light, compared with a control group of 5.6 million individuals who were not vaccinated, it said.

The data comes as Russia battles soaring infections and hesitancy about vaccines at home, while struggling to compete with more established vaccines developed by Pfizer, Moderna and AstraZeneca which are each making hundreds of millions of doses.

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, although there is no consensus among scientists about how broadly they should be used.

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, RDIF, which markets Sputnik V internationally, said in a statement.

RDIF said Sputnik Light would be over 83 per cent effective against infection and over 94 per cent effective against hospitalisation.

Kirill Dmitriev, head of the RDIF, told Reuters he expected Sputnik Light to eventually become the main Russian vaccine against Covid-19.

"Eventually, we believe that Sputnik Light could be the main vaccine one year from now when many people will just need to get revaccinated or will have had Covid and won’t need Sputnik V,” said Dmitriev. — Reuters