A medical worker takes a swab sample from a resident for COVID-19 nucleic acid testing in Wuhan, central China's Hubei Province, Aug. 3, 2021. Wuhan City, capital of central China's Hubei Province, launched another citywide COVID-19 nucleic acid testing campaign on Tuesday, according to a press conference held by the provincial COVID-19 prevention and control headquarters. Wuhan, once hard-hit by COVID-19, identified new local clusters of cases on Monday when seven migrant workers at the Wuhan Economic & Technological Development Zone tested positive for the coronavirus. (Photo by Wu Zhizun/Xinhua)
