Russia is starting its Covid-19 vaccination programme, with clinics in the capital Moscow inoculating those most at risk from the virus.
Its own vaccine Sputnik V, which was registered in August, is being used.
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 in the city of 13 million who work 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.
They will operate from 08:00 until 20:00 local time (05:00-17:00 GMT).
People who have received injections in the last 30 days or who have had respiratory diseases within the last two weeks will be excluded, as will those with certain chronic illnesses, and pregnant and breastfeeding women.
Each person will receive two injections, the second 21 days after the first.