Shanghai reported eight local COVID-19 cases on Saturday, with 366 others testing positive yet showing no symptoms.

Wu Jinglei, director of municipal health commission, said a total of 18,646 close contacts and 51,744 secondary contacts in the city have been tested and quarantined since the current outbreak. 

Wu said the commission has made plans and prepared medical resources in advance for the surge of COVID-19 cases based on the principle of "better having resource left unused than having no resource when in need."

"Hospitals, hospital branches and beds were designated as backup treatment facilities for COVID-19 patients since the early days of this current outbreak," he said.

"In the aspect of human resources, we have formed reserve intensive care teams from municipal-level hospitals to provide treatment for patients who develop severe symptoms in designated hospitals," Wu added.

"They are mobile teams with full treatment capacity, ready to go to any hospital and start giving treatment at once."

Health workers have conducted grid-screening testings in several areas in the city since Wednesday based on risk assessment.

Wu Fan, member of the expert team leading the Shanghai COVID-19 prevention and control efforts, said many cases were found in the grid-screening test at the sub-district and township level.

"Some sub-districts will have to remain shut down for a further round of test as cases were found scattered in the area in the previous test," she said. "These tests are necessary to stamp out the potential and hidden risk, so that we can achieve zero COVID infections outside the transmission links."