The Russian Direct Investment Fund (RDIF) proposes to US drugmaker Pfizer to start joint trials with Sputnik Light as booster COVID-19 vaccine shot, the RDIF said on Wednesday.

The fund published a message on Sputnik V’s official Twitter page.

Delta cases surge in US & Israel shows mRNA vaccines need a heterogeneous booster to strengthen & prolong immune response.#SputnikV pioneered mix&match approach, combo trials & showed 83.1% efficacy vs Delta.
Today RDIF offers Pfizer to start trial with Sputnik Light as booster pic.twitter.com/BTZEhyhWWw

— Sputnik V (@sputnikvaccine) August 11, 2021