Belarus and Argentina launched mass coronavirus vaccinations with the Russian-developed Sputnik V shot on Tuesday, becoming the first countries outside Russia to roll out the vaccine, which is still undergoing late-stage studies to ensure its safety and effectiveness.

The first batch of Sputnik V arrived in the former Soviet republic of Belarus on Tuesday, according to a joint statement by the Belarusian Health Ministry, the Russian Health Ministry and the Russian Direct Investment Fund that bankrolled development of the jab.

“A new stage starts in Belarus today with mass vaccinations against COVID-19. Medical staff, teachers, and those who come into contact a lot of people due to their jobs will be the first to get vaccinated. Vaccination will be entirely voluntary,” Belarus Health Minister Dmitry Pinevich was quoted in the statement as saying.

Hours later, a similar campaign kicked off in South America as Argentine medical workers began receiving the vaccine and officials insisted it was safe. President Alberto Fernandez called it the largest vaccination campaign in the country’s modern history.

Teachers, those with complicating medical conditions and people over 60 were to be next in line in Argentina, which so far has received 300,000 doses, which also will be free and voluntary.

Argentina, a country of 45 million people, has recorded nearly 1.6 million infections with the new coronavirus and almost 43,000 deaths.

Belarus conducted its own trial of Sputnik V among 100 volunteers and gave the shot regulatory approval on Dec. 21, two days before Argentina did.

Russia has been widely criticized for giving the domestically developed Sputnik V regulatory approval in August after the vaccine only had been tested on a few dozen people. An advanced study among tens of thousand started shortly after the vaccine received the Russian government’s go-ahead.

Despite warnings to wait for the results of the study, Russian authorities started offering it to people in high-risk groups – such as medical workers and teachers – within weeks of approval. This month, mass vaccinations with Sputnik V started in Russia, even though it is still undergoing the late-stage trial.

Belarus has reported nearly 190,000 confirmed coronavirus cases and about 1,400 deaths since the start of the pandemic, but many in the Eastern European nation of 9.4 million people suspect that authorities are manipulating statistics to hide the true scope of the country’s outbreak.

President Alexander Lukashenko, who has faced months of demands by protesters to step down after an August election they say was fraudulent, has cavalierly dismissed the coronavirus. He shrugged off the fears and national lockdowns the new virus had caused as “psychosis” and advised citizens to avoid catching it by driving tractors in the field, drinking vodka and visiting saunas.

His attitude has angered many Belarusians, adding to the public dismay over his authoritarian style and helping to fuel months of post-election protests.

Opposition figures say Lukashenko’s government has allowed COVID-19 to run rampant in jails where it has detained thousands of protesters.