Datong

Ten minutes later, the health code turned green, and the pandemic prevention workers at the station allowed Wang to leave Datong, she said.

In March, she travelled to Datong, an industrial coal-mining hub in northern China, to offer counseling.

The day after Wang arrived in Datong, she said her local code turned yellow, which meant she would have to be centrally quarantined in a hotel.

Over the past week, authorities have raced to get a handle on rising cases in cities across China, including Datong, Xining, Nanjing, Xian, Zhengzhou and Wuhan, forcing temporary lockdown measures.

Datong, which recorded 288 cases from Oct. 27-30, has enforced stricter isolation and management of hotels, key industries and its railway.