A medical worker takes swab samples for nucleic acid testing at a sampling site during the latest COVID-19 outbreak in Yinchuan, northwest China's Ningxia Hui Autonomous Region, Oct. 23, 2021. Thousands of medical workers are on duty around the clock at more than 500 sampling sites in key districts of Yinchuan to conduct the test. (Xinhua/Feng Kaihua)
