Russia begins its Covid-19 vaccination programme in some clinics at Moscow, starting with those who are at most risk from the virus.
Its own vaccine Sputnik V, which was registered in August, is being used, reports BBC.
Developers say it is 95% effective and causes no major side effects, but it is still undergoing mass testing.
Thousands of people have already registered to get the first of two jabs over the weekend, but it is unclear how much Russia can manufacture.
Producers are only expected to make two million doses of the vaccine by the end of the year.
Moscow Mayor Sergei Sobyanin, who announced the programme earlier in the week, said it was being offered to people working in schools and the health service, and social workers.
He said the list would grow as more of the vaccine became available.
An online registration service allows city residents in the above professions aged 18-60 to book free appointments at 70 sites around the city.
So far Russia has recorded 2,382,012 cases of the virus, and 41,730 deaths.
Moscow is the centre of the pandemic in Russia, recording thousands of cases and dozens of deaths daily.
But Russia's government has ruled out a lockdown, making the need for an effective vaccine urgent, says the BBC's Sarah Rainsford in Moscow.