Shanghai will continue to operate a number of makeshift hospitals while closing some of the district-level ones as the city has effectively curbed the community transmission of COVID-19 in the current outbreak, the municipal government said on Friday.

The city has been experiencing a decline in the number of daily new infections in the past two weeks, Wu Qing, vice-mayor of Shanghai, said on Friday.

Jiading district on Thursday became the seventh district to achieve zero-COVID outside quarantine areas, and new infections in the city had fallen to 245 confirmed cases and 4,024 asymptomatic carriers that same day, Wu said.

"But the risk of infection flareups among key groups of people in some key areas remains, and the task of epidemic control remains tough," Wu said.

He noted that Shanghai has reported 597,424 local COVID-19 infections, and 871 imported cases since March 1.

As of Thursday, a total of 481,881 patients had recovered and were discharged from hospitals, while 114,971 patients were receiving treatment.

"We are firmly carrying out COVID-19 clearing actions," Wu said.

"We're determined to win this war of defending Shanghai."

The actions include mass testing, stringent community control, enhancement of treatment capacity and medical supplies, as well as guaranteeing people's livelihoods and resumption of work and production.

"We will continue to optimize resources for designated hospitals, makeshift hospitals and quarantine facilities," Wu said.

"Some temporary quarantine facilities of poor quality will be closed, and we will prioritize the closure of makeshift hospitals in school campuses."

The number of COVID-19 patients receiving treatment and under medical observation in makeshift hospitals in Shanghai have more than halved from the peak, according to Wu.

There were 86,400 patients receiving treatment in municipal-level makeshift hospitals and another 184,800 people in district-level makeshift hospitals at the peak of the latest outbreak.

The current numbers are 39,600 and 76,500 respectively.

The future new infections will be transported mainly to municipal-level makeshift hospitals, Wu added.

Zhao Dandan, deputy director of the municipal health commission, said all the hospitals and medical institutes are resuming normal operation for both emergency and outpatient services with careful epidemic prevention measures since Sunday.

Buffer zones were established for emergency medical service, so that patients can receive treatment immediately while waiting for their nucleic acid tests, Zhao said.

Nearly 1.14 million people have made hospital visits in the past week, with the average number of daily visits up 50 percent compared with early April, he said.