Dalian, Liaoning province, reported four new asymptomatic cases of COVID-19 on Tuesday. They were discovered while people were undergoing routine nucleic acid testing at Dalian Port Yidu Cold Chain Co.

According to the city's office for coordinating COVID-19 prevention and control and economic and social development, people who had close contact with the asymptomatic individuals, and in turn their own close contacts, are being fully investigated and quarantined for medical observation.

The cold chain goods have been sealed and the products involved have not entered the market.

As soon as it received the report, the office immediately launched an emergency response plan, set up special teams and formed 12 working groups, including epidemiological investigation, disinfection and nucleic acid testing to quickly carry out epidemiological investigations and quarantine close contacts.

A worker at Dalian Kaiyang World Seafood Co was reported as a new domestically transmitted confirmed case on July 22, breaking the city's record of no new local confirmed cases in more than 100 days.

On Aug 18, the office released a work program to further strengthen epidemic prevention and control in the cold chain sector, requiring that every batch of imported aquatic products and meat should be tested before storage and before leaving the factory. Employees and the environment undergo routine nucleic acid testing every two weeks.

The city's last outbreak ended on Aug 29, when all the 92 confirmed cases and 26 asymptomatic ones were discharged from the hospital.