The port city of Dalian, in northeastern Liaoning Province, has tightened coronavirus control measures and accelerated nucleic acid testing after entering "wartime mode" amid the latest local cluster outbreak, which brought 19 confirmed patients and 20 silent carriers between December 15 and 24.

Dalian reported seven new local confirmed patients (one was a silent carrier) and one asymptomatic patient on Thursday. All the newly confirmed patients live in Jinpu New District, where this wave of outbreak started, the state media reported.

On Friday, the local government asked all residents in Jinpu and five other main districts to receive nucleic acid tests at their nearest sampling sites before 12:00pm that day. Those who refuse to be sampled and cause further spread of the virus will be investigated for legal responsibility according to law, it said.

To reduce the possible risk of virus infection, several medical institutions in Dalian announced on Thursday and Friday that they have suspended part of their usual clinic services.

A total of 129 flights had been canceled as of 9:50 am Friday in Dalian, accounting for 34.7 percent of all the local flights that day, data from Flight Master showed. Earlier, Dalian started citywide nucleic acid testing on Tuesday and regulated that only residents with negative test results are allowed to leave the city.

The annual national entrance exam for postgraduate studies is scheduled to take place over the coming weekend. Local authorities asked candidates in five subdistricts of Jinpu New District with relatively higher virus transmission risk to live separately at five designated hotels without charging them fees.

In Shenyang, the capital city of Liaoning, close to Dalian, candidates from Jinpu New District also have to sit the exam under quarantine. "All the quarantined candidates must receive nucleic acid tests two days before the exam," the Shenyang Examinations Authority said on its website on Thursday.

Dalian announced it will enter "wartime mode" on Sunday, following a local confirmed case – a 39-year-old restaurant chef – reported the day before.

A 10-person working group, consisting of experts in the fields of epidemiology, virology, and disease prevention and control, was sent to Dalian by the National Health Commission on Tuesday to guide local investigation and response.

This wave of Dalian started on December 15, when the city reported four asymptomatic patients who work as loaders in a cold-chain import company. The local government later said it had sealed off related cold-chain foods, and none of the affected products have reached the market.

Dalian adds seven more virus patients, battling new outbreak of dozens sickened in 10 days