MOSCOW — Vaccination against COVID-19 with the Russian-developed Sputnik V vaccine has started in all Russian regions, Russian authorities said Tuesday.

President Vladimir Putin ordered the government to start “large-scale” vaccination in Russia two weeks ago, even though the Sputnik V vaccine is still undergoing advanced studies needed to ensure its safety and effectiveness. The shots have been offered to medical workers for several months even though the vaccine was still in the middle of late-stage trials, and over 150,000 people in Russia have already been vaccinated, according to its developers.

Health Minister Mikhail Murashko said Tuesday the vaccine has been delivered to all Russian regions, and the shots are being administered in over 1,200 medical facilities across the country. Medical workers, teachers and social workers are the first in line to get the shots.

Russia’s state coronavirus task force has reported over 2.7 million confirmed cases in the pandemic and nearly 48,000 deaths. The Russian Sputnik V vaccine received regulatory approval in August in a move that drew international criticism, as by that time the shots had only been tested on a few dozen people.