(ANSA) - BELGRADE, FEB 22 - An additional 50,000 doses of the Russian Sputnik V vaccine against Covid reached Serbia on Monday morning, the country in the western Balkans which has been most successful in its mass vaccination campaign. So far, about 1.2 million (17% of the population) have received the first dose while over 400,000 have also received the second. Sputnik V is one of four vaccines available in Serbia, together with China's Sinopharm, Pfizer-BioNTech and AstraZeneca. Premier Ana Brnabic confirmed that on Monday a further 46,800 doses of Pfizer-BioNTech will arrive during the day, with provisions to Serbia overall totaling two million doses. The Balkan country has reached an agreement with Russia for the production on its territory of Sputnik V, which could begin by the end of this year. Together with other countries in the Balkan region, Serbia is included in a list of countries benefiting from the Covax plan for low-income States but Belgrade over the past few months - thanks to more financial availability - and good relations between President Aleksandar Vucic and the leaders of Russia and China - has decided to move autonomously, forging bilateral agreements with vaccine producers. This has enabled Serbia to donate vaccines to neighboring countries. (ANSA).