Massive COVID-19 nucleic acid test held in Xining

A medical worker collects a swab sample from a resident at a COVID-19 testing site in Chengxi District of Xining, northwest China's Qinghai Province, Nov. 2, 2021. Xining has set up 121 testing sites in Chengxi District for massive COVID-19 nucleic acid testing. (Xinhua/Zhang Manyi)

A medical worker collects a swab sample from a resident at a COVID-19 testing site in Chengxi District of Xining, northwest China's Qinghai Province, Nov. 2, 2021. Xining has set up 121 testing sites in Chengxi District for massive COVID-19 nucleic acid testing. (Xinhua/Zhang Manyi)

Residents scan a QR code to have their personal information registered at a COVID-19 testing site in Chengxi District of Xining, northwest China's Qinghai Province, Nov. 2, 2021. Xining has set up 121 testing sites in Chengxi District for massive COVID-19 nucleic acid testing. (Xinhua/Zhang Manyi)

A medical worker collects a swab sample from a resident at a COVID-19 testing site in Chengxi District of Xining, northwest China's Qinghai Province, Nov. 2, 2021. Xining has set up 121 testing sites in Chengxi District for massive COVID-19 nucleic acid testing. (Xinhua/Zhang Manyi)

A medical worker collects a swab sample from a child at a COVID-19 testing site in Chengxi District of Xining, northwest China's Qinghai Province, Nov. 2, 2021. Xining has set up 121 testing sites in Chengxi District for massive COVID-19 nucleic acid testing. (Xinhua/Zhang Manyi)