Scientists raise concerns after Russia gives go-ahead before full trials to test safety, efficacy have been completed.
Moscow has started vaccinating workers at high risk of becoming infected with the coronavirus at newly opened clinics across the city.
It started the distribution of the Sputnik V COVID-19 shot via 70 clinics on Saturday, marking Russia’s first mass vaccination against the disease.
The vaccine, made in Russia, would first be made available to doctors and other medical workers, teachers and social workers because they ran the highest risk of exposure to the disease.
It works in a manner similar to the vaccine that is being developed by the Oxford-AstraZeneca team in the UK, using other viruses to deliver molecules from the coronavirus that causes COVID-19 into human bodies in order to stimulate an immune response.
It is administered in two injections given 21 days apart.
The move comes as Russia reported a record high of 28,782 new COVID-19 cases on Saturday, including 7,993 in Moscow, taking the national total to 2,431,731 since the pandemic began.
Authorities confirmed 508 deaths related to COVID-19 in the past 24 hours, pushing the official national death toll to 42,684.
“Over the first five hours, 5,000 people signed up for the jab – teachers, doctors, social workers, those who are today risking their health and lives the most,” Mayor Sergei Sobyanin wrote on his personal website on Friday.
Al Jazeera’s Aleksandra Godfroid, reporting from Moscow, said there is an hour allocated for each patient.
“The first 10 minutes are for a general health check-up,” she said. “The next 15 minutes are to prepare the vaccine because it has to be kept at -18C, and then half an hour for observing the person.”
Those who will take the vaccine must come back in three weeks to receive their second shot.
“According to Russian officials, they should build up their full immunity after 42 days,” she added.
The age for those receiving shots is capped at 60. People with certain underlying health conditions, pregnant women and those who have had a respiratory illness for the past two weeks are barred from vaccination.
Russia has developed two COVID-19 vaccines: Sputnik V is backed by the Russian Direct Investment Fund as well as another developed by Siberia’s Vector Institute.
Final trials for both are yet to be completed.
Scientists have raised concerns about the speed at which Russia has worked, giving the regulatory go-ahead for its vaccines and launching mass vaccinations before full trials to test safety and efficacy had been completed.
“The scepticism around this comes from the fact that it’s been developed very quickly and it appears to be put to the general population rather earlier than it would do if it had been developed, say in the UK,” said Simon Clarke, an assistant professor at the University of Reading.
“Because they’ve used such small study groups, claiming a 95 percent efficacy at this stage may be a bit premature,” he added. “It needs to be remembered they are not administering it to people over the age of 60 and really, they’re the biggest at-risk group.”