Mask marks are seen on the face of nurse Zhang Xianghan in Wuhan, central China's Hubei Province, Aug. 6, 2021. To promptly contain the latest COVID-19 resurgence, central China's Wuhan collected over 10.3 million samples for nucleic acid testing in three days, local authorities said Friday.Photo:Xinhua

Nurse Zhang Xianghan takes a swab sample from a resident for COVID-19 nucleic acid testing in Wuhan, central China's Hubei Province, Aug. 6, 2021.Photo:Xinhua

Nurse Zhang Xianghan takes a swab sample from a resident for COVID-19 nucleic acid testing in Wuhan, central China's Hubei Province, Aug. 6, 2021.Photo:Xinhua

A community worker helps residents with nucleic acid testing registry in Wuhan, central China's Hubei Province, Aug. 4, 2021. Photo:Xinhua

Nurse Han Miaomiao takes a swab sample from a resident for COVID-19 nucleic acid testing in Wuhan, central China's Hubei Province, Aug. 4, 2021.Photo:Xinhua