A medical staff member (L) collects a worker's throat swab sample at a COVID-19 nucleic acid testing facility set up temporarily on a construction site in Haidian District of Beijing, capital of China, June 26, 2020. More than 1,750 construction workers in Beijing received COVID-19 nucleic acid tests on Friday. [Photo by Ren Chao/Xinhua]

A staff member (L, front) disinfects a COVID-19 nucleic acid testing facility set up temporarily on a construction site in Haidian District of Beijing, capital of China, June 26, 2020. More than 1,750 construction workers in Beijing received COVID-19 nucleic acid tests on Friday. [Photo by Ren Chao/Xinhua]

Workers wait to have their throat swab samples collected at a COVID-19 nucleic acid testing facility set up temporarily on a construction site in Haidian District of Beijing, capital of China, June 26, 2020. More than 1,750 construction workers in Beijing received COVID-19 nucleic acid tests on Friday. [Photo by Ren Chao/Xinhua]

A staff member (R, front) disinfects a COVID-19 nucleic acid testing facility set up temporarily on a construction site in Haidian District of Beijing, capital of China, June 26, 2020. More than 1,750 construction workers in Beijing received COVID-19 nucleic acid tests on Friday. [Photo by Ren Chao/Xinhua]