Beijing is facing a major test of its COVID-19 prevention and control as new cases have occurred recently in several districts, a senior city official said on Friday.

The municipal government suggests local residents spend the New Year's and Spring Festival holidays in the city to reduce the risk of infection, said Chen Bei, deputy secretary-general of the Beijing municipal government. Spring Festival is in mid-February this year.

"Citizens should not leave the city if not necessary," she said. "Large-scale events should not be held."

Zhu Sheng, deputy administrator of Chaoyang district, said officials received a report on Thursday morning that an Asiana Airlines employee who lived and worked in the Maizidian Street area in Chaoyang tested positive for COVID-19 after traveling to South Korea from Beijing on Tuesday.

The South Korean government confirmed that the employee was asymptomatic as of Thursday night.

The living space and workplace of the employee was disinfected immediately and 43 close contacts were placed under medical observation, Zhu said.

By 4 pm on Friday, 4,345 test samples had been collected and all 1,684 results that had been processed were negative.

To help curb the outbreak in Dalian, the National Health Commission has sent a working group to the Liaoning province port, the commission said Friday.

Dalian reported seven new confirmed cases and one asymptomatic infection on Thursday. One confirmed patient was previously asymptomatic, the local health commission said.

As of Thursday, the city had reported 19 confirmed COVID-19 cases and 20 asymptomatic infections since new infections emerged on Dec 15.

With the national postgraduate entrance exams starting on Saturday, all Chinese cities, particularly cities like Beijing and Dalian that have reported new cases of the virus, are making every effort to ensure exams are conducted in a safe and smooth manner.

The candidates are required to present negative nucleic acid tests done within seven days before taking the exams.

Wen Zhihao, 21, a student who planned to take the exam in Beijing, said that he trusts the city's prevention and control measures and that the new cases had not affected his mood at all.

Zhao Yang, director of Dalian's education bureau, said designated exam rooms and hotels have been prepared to host candidates from the city's five closed-off neighborhoods from Friday morning to Monday. The test-takers will stay at the hotels during the exam period.

Expenses will be covered by the Dalian Jinpu New Area, where the neighborhoods, test-taking facilities and hotels are located.

"Fortunately, Dalian has made adjustments very quickly. We were worrying that my sister might miss the exam since she could not leave the area to get to her original testing center in downtown Dalian," said Qiu Tiantian, whose 24-year-old sister is a candidate for the exams.

Wu Zunyou, chief epidemiologist at the Chinese Center for Disease Control and Prevention, said it's normal for China to have recently had new COVID-19 cases in some places given that the pandemic is still growing worldwide, adding that rising cases are a reminder to stick to prevention and control measures to avoid risks.

Wu told China Central Television on Thursday that many of the positive test results that have been reported in China recently have been asymptomatic patients, indicating that risks have been discovered before they spread widely thanks to multiple measures, including testing.