A medical worker takes a swab sample from a resident for nucleic acid test at a COVID-19 testing site in a residential community of Nankai district in North China's Tianjin, Jan 20, 2022. The city launched its fourth citywide nucleic acid testing at 6 am on Jan 20, aiming to curb the further spread of the virus.[Photo/Xinhua]
A medical worker takes a swab sample from a resident for nucleic acid test at a COVID-19 testing site in Hedong district in North China's Tianjin, Jan 20, 2022. [Photo/Xinhua]
Residents and volunteers queue up for nucleic acid tests at a residential community in Nankai district of North China's Tianjin, Jan 20, 2022. [Photo/Xinhua]
Medical workers head for a COVID-19 testing site at dawn in North China's Tianjin, Jan 20, 2022. [Photo/Xinhua]
A resident arrives to receive nucleic acid test at a COVID-19 testing site in a residential community of Nankai district in North China's Tianjin, Jan 20, 2022. [Photo/Xinhua]
A medical worker takes a swab sample from a resident for nucleic acid test at a COVID-19 testing site in Hedong district in North China's Tianjin, Jan 20, 2022. [Photo/Xinhua]
A medical worker takes a swab sample from a resident for nucleic acid test at a COVID-19 testing site in a residential community of Nankai district in North China's Tianjin, Jan 20, 2022. [Photo/Xinhua]
A medical worker wearing protective suit works at a COVID-19 testing site in Hedong District in North China's Tianjin, Jan 20, 2022. [Photo/Xinhua]
A medical worker takes a swab sample from a resident for nucleic acid test at a COVID-19 testing site in a residential community of Nankai district in North China's Tianjin, Jan 20, 2022. [Photo/Xinhua]
Staff members prepare medical materials for nucleic acid tests at a COVID-19 testing site in a residential community of Nankai district in North China's Tianjin, Jan 20, 2022. [Photo/Xinhua]
