Medical staff members take throat swab samples from construction workers at a temporary sampling site in Daxing District of Beijing, capital of China, July 2, 2020. A total of 1,353 workers at the construction site had their samples collected for nucleic acid tests on Thursday. (Xinhua/Cai Yang)

Medical staff members take throat swab samples from construction workers at a temporary sampling site in Daxing District of Beijing, capital of China, July 2, 2020. A total of 1,353 workers at the construction site had their samples collected for nucleic acid tests on Thursday. (Xinhua/Cai Yang)

Medical staff members take throat swab samples from construction workers at a temporary sampling site in Daxing District of Beijing, capital of China, July 2, 2020. A total of 1,353 workers at the construction site had their samples collected for nucleic acid tests on Thursday. (Xinhua/Cai Yang)

Construction workers line up at a temporary sampling site in Daxing District of Beijing, capital of China, July 2, 2020. A total of 1,353 workers at the construction site had their samples collected for nucleic acid tests on Thursday. (Xinhua/Cai Yang)

Construction workers line up at a temporary sampling site in Daxing District of Beijing, capital of China, July 2, 2020. A total of 1,353 workers at the construction site had their samples collected for nucleic acid tests on Thursday. (Xinhua/Cai Yang)