All residential communities and streets in Beijing's Shunyi district, where new COVID-19 cases were recently reported, have strengthened their virus prevention and control measures to cut infection, a senior official said at a news conference on Monday.

Zhi Xianwei, executive deputy head of the district, said emergency measures have been implemented, including closed management, disinfection and large-scale testing.

By Monday afternoon, the authority identified 891 close contacts and 618 secondary close contacts of previously reported COVID-19 cases.

By 3 pm Monday, the district had collected 1,207,657 samples. Among these, 901,206 all showed negative results.

Beijing has entered a state of emergency, as the number of COVID-19 cases rose over the past few days.

Xu Hejian, spokesman for the municipal government, said the city still faces a complicated situation in terms of coronavirus control and prevention.

The city reported one imported case on Sunday.

On Saturday, Beijing reported five confirmed cases and one asymptomatic case, all domestically transmitted and all related to a previously confirmed case.

In response, two villages in Shunyi district, where infected patients live or work, have been designated as medium-risk areas starting Sunday, according to Pang Xinghuo, deputy director of the municipal center for disease control and prevention.

Li Yi, spokesman for the Beijing Education Commission, said college students should go back home for their winter vacation on a staggered schedule in order to reduce the risk of infection.