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.Photo:Xinhua

Health authorities in Northwest China's Xinjiang Uygur Autonomous Region said on Sunday that they would launch a second round of large-scale testing in major districts around Urumqi to pinpoint false-negative residents.  

Zhang Wei, director of the Urumqi health committee, said at a press conference that false-negative results are possible due to various reasons. People who have had contact with confirmed patients or suspected patients, or those who have been to high and middle-risk areas, have to undergo nucleic acid tests twice and get negative results to be clarified suspicious. 

The second screening started from Sunday with the focus on high-risk areas like Tianshan and Saybagh districts in the city, according to Zhang. 

Since July 15, when this wave of the outbreak appeared in Xinjiang, the region has reported 137 confirmed COVID-19 cases with 135 located in Urumqi city.

The region has witnessed double-digit growth in new cases for four days with 22 on Saturday, 20 on Friday, 13 on Thursday and 18 on Wednesday. 

Many of the new confirmed cases are previous silent carriers or suspected patients who have already been discovered and are under observation, so it does not necessary mean that the infection is still spreading, according to Rui Baoling, director of the disease control and prevention center in Urumqi.

More sporadic cases and silent virus carriers will be confirmed along with the expansion of testing, said Rui on Friday at a press conference, asking local residents not to panic and cooperate to implement anti-epidemic measures. 

With a population of 3.5 million people, Urumqi has sampled more than 2.3 million people in COVID-19 nucleic acid tests, according to the Friday press conference.