Moscow has launched a mass screening programme for coronavirus antibodies, inviting people chosen at random from various age groups to clinics across the city.
The hope is that the test results can allow the authorities to map their way out of lockdown, despite uncertainty over how much immunity to Covid-19 the antibodies actually provide.
Russia currently has one of the world’s highest rates of coronavirus infection, with 10,598 new cases detected on Friday.
The BBC’s Sarah Rainsford has visited one of the testing centres.
Video produced by Anton Chicherov and Liza Shuvalova