After it reported two domestic COVID-19 cases on Sunday, Shanghai carried out over 2,500 nucleic acid tests of people and more than 130,000 cold chain food sampling tests for the novel coronavirus, and the results were all negative, the Shanghai Municipal Health Commission said Monday at a press conference. 

The two domestic cases on Sunday, including a cargo handler at the airport, brought the total number of confirmed cases since Friday to five.

As of 8:00 a.m. on Monday, 55 close contacts of the two cases had been traced. All were under quarantine and observation, and their first nucleic acid sampling had been completed, with the test results all negative.

Another 2,541 screening contacts were also tested, and food, articles and locations linked to the two new cases were sampled.

Shanghai Pudong Airport started testing all staff on Sunday night after the airport found several cargo handlers and close contacts tested positive for the coronavirus over the past several days. 

A notice circulating online showed that all staff in the two main cargo zones of the airport were being required to complete nucleic acid tests at the P4 parking lot of Pudong Airport by midnight Sunday.

Flights into Shanghai were largely cancelled on Sunday night. As of 11:00 pm, 277 flights had been cancelled, according to figures compiled by airline data tracker VariFlight app.

Xu Jin, deputy director of the Shanghai Municipal Market Supervision Bureau, laid out the measures that the Shanghai regulatory authorities had taken to prevent cold chain food contamination and avoid a spread of the novel coronavirus. 

The bureau and other departments organized and carried out special inspections of large aquatic product wholesale markets (seafood markets), frozen and refrigerated meat, aquatic product production and processing enterprises, and cold storage, Xu said. 

"Shanghai regulatory authorities have promoted 405 cold chain food production, processing, distribution, storage, transportation, catering services and other production and operation enterprises to be included in the traceability system, and cumulatively uploaded more than 3 million pieces of traceable data on meat, aquatic products and other cold chain foods," he added.

Previous cases of COVID-19 in China have been linked to cold chain food or wholesale markets. 

At present, Shanghai is making every effort to complete the epidemiological investigation and nucleic acid testing of relevant personnel, so as to ensure that all investigations and inspections are required, Xu said.

"In the next step, Shanghai will continue to strengthen the closed-loop control of the entire cold chain food process, and make every effort to ensure market supply"