Residents wait in line for nucleic acid tests at a community in Qiaoxi District of Shijiazhuang, capital of north China's Hebei Province, Jan. 6, 2021. Shijiazhuang started to conduct citywide nucleic acid tests covering all citizens on Wednesday. (Photos: Xinhua)

Medical workers collect swab samples from residents at a community in Qiaoxi District of Shijiazhuang, capital of north China's Hebei Province, Jan. 6, 2021. Shijiazhuang started to conduct citywide nucleic acid tests covering all citizens on Wednesday.

Photo taken with a mobile phone shows a medical worker collecting a swab sample from a resident at a community in Qiaoxi District of Shijiazhuang, capital of north China's Hebei Province, Jan. 6, 2021. Shijiazhuang started to conduct citywide nucleic acid tests covering all citizens on Wednesday.

A medical worker collects a swab sample from a resident at a community in Qiaoxi District of Shijiazhuang, capital of north China's Hebei Province, Jan. 6, 2021. Shijiazhuang started to conduct citywide nucleic acid tests covering all citizens on Wednesday.

Photo taken with a mobile phone shows a medical worker collecting a swab sample from a resident at a community in Qiaoxi District of Shijiazhuang, capital of north China's Hebei Province, Jan. 6, 2021. Shijiazhuang started to conduct citywide nucleic acid tests covering all citizens on Wednesday.

Residents register for nucleic acid tests at a community in Yuhua District of Shijiazhuang, capital of north China's Hebei Province, Jan. 6, 2021. Shijiazhuang started to conduct citywide nucleic acid tests covering all citizens on Wednesday.

Medical workers collect swab samples from residents at a community in Qiaoxi District of Shijiazhuang, capital of north China's Hebei Province, Jan. 6, 2021. Shijiazhuang started to conduct citywide nucleic acid tests covering all citizens on Wednesday.

A medical worker adjusts her face shield at a coronavirus testing site in Qiaoxi District of Shijiazhuang, capital of north China's Hebei Province, Jan. 6, 2021. Shijiazhuang started to conduct citywide nucleic acid tests covering all citizens on Wednesday.

A medical worker collects a swab sample from a resident at a community in Qiaoxi District of Shijiazhuang, capital of north China's Hebei Province, Jan. 6, 2021. Shijiazhuang started to conduct citywide nucleic acid tests covering all citizens on Wednesday.

A medical worker collects a swab sample from a resident at a community in Yuhua District of Shijiazhuang, capital of north China's Hebei Province, Jan. 6, 2021. Shijiazhuang started to conduct citywide nucleic acid tests covering all citizens on Wednesday.

A medical worker collects a swab sample from a resident at a community in Qiaoxi District of Shijiazhuang, capital of north China's Hebei Province, Jan. 6, 2021. Shijiazhuang started to conduct citywide nucleic acid tests covering all citizens on Wednesday.

A medical worker collects a swab sample from a resident at a community in Qiaoxi District of Shijiazhuang, capital of north China's Hebei Province, Jan. 6, 2021. Shijiazhuang started to conduct citywide nucleic acid tests covering all citizens on Wednesday.

Medical workers collect swab samples from residents at a community in Qiaoxi District of Shijiazhuang, capital of north China's Hebei Province, Jan. 6, 2021. Shijiazhuang started to conduct citywide nucleic acid tests covering all citizens on Wednesday.

A medical worker collects a swab sample from a girl at a community in Qiaoxi District of Shijiazhuang, capital of north China's Hebei Province, Jan. 6, 2021. Shijiazhuang started to conduct citywide nucleic acid tests covering all citizens on Wednesday.

A medical worker collects a swab sample from a girl at a community in Qiaoxi District of Shijiazhuang, capital of north China's Hebei Province, Jan. 6, 2021. Shijiazhuang started to conduct citywide nucleic acid tests covering all citizens on Wednesday.

A medical worker collects a swab sample from a resident at a community in Qiaoxi District of Shijiazhuang, capital of north China's Hebei Province, Jan. 6, 2021. Shijiazhuang started to conduct citywide nucleic acid tests covering all citizens on Wednesday.