A medical worker takes a swab sample from a woman 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 July 21. [Photo/Xinhua]
Medical workers take swab samples from residents for COVID-19 test at a testing site in Nanjing, East China's Jiangsu province, July 21, 2021. [Photo/Xinhua]
People register for COVID-19 test at a testing site in Nanjing, East China's Jiangsu province, July 21, 2021. [Photo/Xinhua]
A medical worker takes a swab sample from an elderly man for COVID-19 test at a testing site in Nanjing, East China's Jiangsu province, July 21, 2021. [Photo/Xinhua]
A medical worker takes a swab sample from a woman for COVID-19 test at a testing site in Nanjing, East China's Jiangsu province, July 21, 2021. [Photo/Xinhua]
