A medical worker takes a swab sample from a child for COVID-19 nucleic acid test at a testing site in Siming District of Xiamen, east China's Fujian Province, July 30, 2021. Four people tested positive for novel coronavirus in nucleic acid testing on Friday in the city of Xiamen, east China's Fujian Province, local authorities said. (Photo by Zeng Demeng/Xinhua)
