Sputnik Light-Pfizer Combo Boosts Efficacy Against Delta Variant, Gamaleya Institute Says

MOSCOW (Sputnik) - Those vaccinated with two shots of Pfizer COVID-19 vaccine will see a boosted efficacy against the Delta variant if they receive a shot of Russian Sputnik Light vaccine, Alexander Gintsburg, the director of Moscow-based Gamaleya Research Center for Epidemiology and Microbiology, told Sputnik on 17 August.

On 11 August, the Russian Direct Investment Fund (RDIF), which markets the Russian vaccine abroad, proposed to US drugmaker Pfizer to start joint trials with Sputnik Light as a booster third shot.

"The move by the RDIF to propose Pfizer boosting with Sputnik Light is quite reasonable, those who are vaccinated with Pfizer could be better protected by a wide range of antibodies which they will generate after the boost," Gintsburg said.

Pfizer efficacy against the Delta variant is still unclear.

Sputnik V efficacy against the Delta variant was estimated by the Russian Health Ministry at 83.1%. Meanwhile, Pfizer efficacy against COVID-19 dropped in July when the Delta variant became dominant, according to a report, published on MedRxiv, a website server distributing e-prints in the health sciences still not reviewed by peers. It estimated the Moderna vaccine efficacy against the Delta strain at 76% and Pfizer at 42%.

The single-dose Sputnik Light vaccine was registered early in May in Russia, with its efficacy at 79.4%. Sputnik Light is the first Sputnik V component, with no severe side effects.