Shanghai's health authority said all districts will strictly carry out a “zero reporting” mechanism on fever cases. Three types of people are targets of the mechanism, officials told a news conference on Friday.

Targeted groups include people who are undergoing quarantine and observation at home or designated places after coming from or via key areas of the epidemic; people who return to Shanghai to work in education, medical services, home services, nursing and labor-intensive plants and companies, as well as staff serving in property management, logistics and public transportation; and people coming or returning to Shanghai from other regions after February 10.

“Every district should collect reports from all subdistricts and submit to the government every day with data from the previous 24 hours,” said Zheng Jin, a spokeswoman of Shanghai Health Commission.

She also explained the process of ruling out suspected cases.

Every suspected case should receive two nucleic acid tests within at least a 24-hour interval. The diagnosis must be based on clinical and imaging results and receive expert group consultation.

“It takes some time to carefully rule out suspected cases to ensure early detection, quarantine and diagnosis of every patient as well as blocking the spread of the virus,” she said.