A medical worker takes a swab sample from a resident for COVID-19 nucleic acid testing at a community in Erqi District of Zhengzhou, central China's Henan Province, July 31, 2021. The central Chinese city of Zhengzhou reported 11 confirmed COVID-19 cases and 16 asymptomatic cases on Saturday, local authorities said. The new infections were screened after the city registered one asymptomatic case on Friday and launched epidemiological investigations and massive nucleic acid testing. (Xinhua/Hao Yuan)
