Reuters.Sputnik Light has already been tested in smaller-scale, Phase I/II clinical trials, Kubataev said, adding that an application for approval of the vaccine based on results from these trials has now been filed."In parallel, we have already launched international clinical Phase III trials," he said, that will test its efficacy.Around 2,000 people have already received the shot, which consists of just one of the two doses, each based on a different adenovirus vector, that make up Sputnik V proper.Moscow has said that its two-dose Sputnik V vaccine will remain the main version used in Russia.