Sputnik V is Russia’s flagship two-dose COVID-19 vaccine. Late last month, the country also announced that it would begin circulation of the one-dose Sputnik Light vaccine, the country’s fourth authorized vaccine against COVID-19.The original vaccine, Sputnik V, which Russia’s Gamaleya Research Institute of Epidemiology and Microbiology developed, consists of two different adenoviruses that require delivery by two separate vaccinations.Both doses contain non-replicating viral vectors.