Medical workers prepare COVID-19 nucleic acid tests at a testing site in Wulingyuan District of Zhangjiajie, central China's Hunan Province, Aug. 8, 2021. Wulingyuan District in the city of Zhangjiajie has launched the fifth round of COVID-19 mass testing on Sunday. (Photo by Wu Yongbing/Xinhua)
A medical worker takes a swab sample from a woman at a COVID-19 nucleic acid testing site in Wulingyuan District of Zhangjiajie, central China's Hunan Province, Aug. 8, 2021. Wulingyuan District in the city of Zhangjiajie has launched the fifth round of COVID-19 mass testing on Sunday. (Photo by Wu Yongbing/Xinhua)
A medical worker takes a swab sample from a woman at a COVID-19 nucleic acid testing site in Wulingyuan District of Zhangjiajie, central China's Hunan Province, Aug. 8, 2021. Wulingyuan District in the city of Zhangjiajie has launched the fifth round of COVID-19 mass testing on Sunday. (Photo by Wu Yongbing/Xinhua)
