Beijing will tighten its epidemic control measures starting Thursday due to the rising number of infections at a high level in recent days, senior officials said on Tuesday.

All people will be required to show negative results of nucleic acid tests taken within 48 hours before entering government departments, office buildings, supermarkets and other public places, as well as taking buses and subways, city spokesman Xu Hejian said at a news conference on Tuesday.

"The current virus variant is extremely infectious and easily concealed, and the city's control and prevention work is at the most critical stage at present," he said.

The authority also suggested the elderly and the young get vaccinated as soon as possible in order to be protected.

"The recently reported two severe COVID-19 cases both had not been vaccinated," Liu Xiaofeng, deputy director of the Beijing Center for Disease Prevention and Control, said at the conference. "Based on data collected from infected people recently, the percentage of vaccinated patients among the infected cases aged above 60 is relatively low. Less than 30 percent of infected patients above 80 have been vaccinated."

Chaoyang, the hardest-hit district during the ongoing outbreak in the capital, reported 128 cases and 655 asymptomatic carriers in total on Monday, representing about half of the confirmed cases in the city and more than half of the city's asymptomatic carriers.

Between midnight and 3 pm on Tuesday, Beijing reported 634 locally transmitted COVID-19 infections, with 490 of them asymptomatic carriers. Among the total infections, 499 were found among those under quarantine and the remaining 135 were detected at the community level.

Chaoyang reported 197 infections during the same period, among whom 51 were found from outside controlled zones.

Thus, the district continued to encourage its residents not to leave the area unless absolutely necessary.

Students in Chaoyang are having classes online and companies have been asked to reduce the number of staff who go to the workplace. People are encouraged to work from home, Yang Beibei, deputy head of Chaoyang district, said on Tuesday.