Medical workers collect swab samples for residents at Tianshan District in Urumqi, northwest China's Xinjiang Uygur Autonomous Region, July 20, 2020. Urumqi is carrying out free nucleic acid tests for all residents and people who are visiting the city, in a bid to screen for novel coronavirus infections and reduce the risk of the epidemic spread. Nearly 2,000 medical workers, distributed in residential communities, are conducting nucleic acid tests for residents in Urumqi. (Photos: Xinhua)

Medical worker Yan Huanjiao collects a swab sample from a resident at Tianshan District in Urumqi, northwest China's Xinjiang Uygur Autonomous Region, July 20, 2020. Urumqi is carrying out free nucleic acid tests for all residents and people who are visiting the city, in a bid to screen for novel coronavirus infections and reduce the risk of the epidemic spread. Nearly 2,000 medical workers, distributed in residential communities, are conducting nucleic acid tests for residents in Urumqi.

Medical worker Liu Hui collects a swab sample from a resident at Tianshan District in Urumqi, northwest China's Xinjiang Uygur Autonomous Region, July 20, 2020. Urumqi is carrying out free nucleic acid tests for all residents and people who are visiting the city, in a bid to screen for novel coronavirus infections and reduce the risk of the epidemic spread. Nearly 2,000 medical workers, distributed in residential communities, are conducting nucleic acid tests for residents in Urumqi.

Medical workers collect swab samples for residents at Tianshan District in Urumqi, northwest China's Xinjiang Uygur Autonomous Region, July 20, 2020. Urumqi is carrying out free nucleic acid tests for all residents and people who are visiting the city, in a bid to screen for novel coronavirus infections and reduce the risk of the epidemic spread. Nearly 2,000 medical workers, distributed in residential communities, are conducting nucleic acid tests for residents in Urumqi.