Nanjing carries out citywide nucleic acid testing

A medical worker takes a swab sample from a man for COVID-19 test at a testing site in Nanjing, east China's Jiangsu Province, July 21, 2021. Nanjing, which has a population of more than 9.3 million, carried out citywide nucleic acid testing starting on Wednesday. (Xinhua/Ji Chunpeng)