Medical staff members process samples collected for COVID-19 tests at a nucleic acid test lab of the Pidu District Hospital of Traditional Chinese Medicine in Pidu District of Chengdu, capital of southwest China's Sichuan Province, Dec. 10, 2020. Chengdu reported zero increase in new domestically transmitted COVID-19 cases and asymptomatic cases from 9 p.m. Tuesday to 6 p.m. Wednesday, while citywide nucleic acid tests are continuing, local authorities said. At the Pidu District Hospital of Traditional Chinese Medicine, medical workers have been working 24 hours nonstop to conduct COVID-19 tests as quickly as possible. (Xinhua/Shen Bohan)

A medical staff member processes samples collected for COVID-19 tests at a nucleic acid test lab of the Pidu District Hospital of Traditional Chinese Medicine in Pidu District of Chengdu, capital of southwest China's Sichuan Province, Dec. 10, 2020. Chengdu reported zero increase in new domestically transmitted COVID-19 cases and asymptomatic cases from 9 p.m. Tuesday to 6 p.m. Wednesday, while citywide nucleic acid tests are continuing, local authorities said. At the Pidu District Hospital of Traditional Chinese Medicine, medical workers have been working 24 hours nonstop to conduct COVID-19 tests as quickly as possible. (Xinhua/Shen Bohan)

A medical staff member processes samples collected for COVID-19 tests at a nucleic acid test lab of the Pidu District Hospital of Traditional Chinese Medicine in Pidu District of Chengdu, capital of southwest China's Sichuan Province, Dec. 10, 2020. Chengdu reported zero increase in new domestically transmitted COVID-19 cases and asymptomatic cases from 9 p.m. Tuesday to 6 p.m. Wednesday, while citywide nucleic acid tests are continuing, local authorities said. At the Pidu District Hospital of Traditional Chinese Medicine, medical workers have been working 24 hours nonstop to conduct COVID-19 tests as quickly as possible. (Xinhua/Shen Bohan)

A medical staff member collects a swab sample from a resident for COVID-19 test at the Pidu District Hospital of Traditional Chinese Medicine in Pidu District of Chengdu, capital of southwest China's Sichuan Province, Dec. 10, 2020. Chengdu reported zero increase in new domestically transmitted COVID-19 cases and asymptomatic cases from 9 p.m. Tuesday to 6 p.m. Wednesday, while citywide nucleic acid tests are continuing, local authorities said. At the Pidu District Hospital of Traditional Chinese Medicine, medical workers have been working 24 hours nonstop to conduct COVID-19 tests as quickly as possible. (Xinhua/Shen Bohan)

A medical staff member informs residents of the dos and don'ts for COVID-19 tests at the Pidu District Hospital of Traditional Chinese Medicine in Pidu District of Chengdu, capital of southwest China's Sichuan Province, Dec. 10, 2020. Chengdu reported zero increase in new domestically transmitted COVID-19 cases and asymptomatic cases from 9 p.m. Tuesday to 6 p.m. Wednesday, while citywide nucleic acid tests are continuing, local authorities said. At the Pidu District Hospital of Traditional Chinese Medicine, medical workers have been working 24 hours nonstop to conduct COVID-19 tests as quickly as possible. (Xinhua/Shen Bohan)