A medical worker collects a swab sample of a student for nucleic acid testing of possible COVID-19 infection at No. 1 Middle School of Lu'an City, east China's Anhui Province, May 14, 2021. Lu'an City is conducting nucleic acid tests for all residents in major urban districts of the city, starting Friday. (Xinhua/Jin Jian)
A medical worker collects a swab sample of a student for nucleic acid testing of possible COVID-19 infection at No. 1 Middle School of Lu'an City, east China's Anhui Province, May 14, 2021. Lu'an City is conducting nucleic acid tests for all residents in major urban districts of the city, starting Friday. (Xinhua/Jin Jian)
A medical worker collects a swab sample of a student for nucleic acid testing of possible COVID-19 infection at No. 1 Middle School of Lu'an City, east China's Anhui Province, May 14, 2021. Lu'an City is conducting nucleic acid tests for all residents in major urban districts of the city. (Photo by Chen Li/Xinhua)
Aerial photo taken on May 14, 2021 shows people waiting for nucleic acid test at a testing site in Lu'an City, east China's Anhui Province. Lu'an City is conducting nucleic acid tests for all residents in major urban districts of the city. (Photo by Chen Li/Xinhua)
A medical worker collects a swab sample of a student for nucleic acid testing of possible COVID-19 infection at No. 1 Middle School of Lu'an City, east China's Anhui Province, May 14, 2021. Lu'an City is conducting nucleic acid tests for all residents in major urban districts of the city. (Photo by Chen Li/Xinhua)
