Hubei province is lowering its level of response to the novel coronavirus outbreak from the highest level on Saturday, but while this measure is taken by China's hardest-hit area, authorities across the nation were urged to remain vigilant against the disease after loopholes were found in epidemic prevention and control in Heilongjiang province.

In a release on Friday, the Joint Prevention and Control Mechanism of the State Council, China's Cabinet, called for better control of hospital infections, stronger nucleic acid testing capabilities and more attention to the risk of imported infections nationwide.

Since April, cluster infections caused by imported cases have resurged in the cities of Harbin and Mudanjiang in Heilongjiang. The infections also affected several hospitals, infecting dozens of people including medical staff.

In April, 131 domestically transmitted infections were reported on the Chinese mainland, of which more than 60 percent resulted from cluster infections in Heilongjiang, Mi Feng, a spokesman for the National Health Commission, said on Friday.

Of the six newly reported domestic cases on Thursday, five were in Heilongjiang and one in the Inner Mongolia autonomous region, he said at a daily briefing.

The authorities in Harbin and Mudanjiang have failed to realize the risk of imported infections, and were lacking in their capability to curb the epidemic, according to the release.

The two cities also failed to implement the 14-day quarantine measure for people returning from overseas.

The resurgence of cluster infections has also exposed loopholes in infection control in hospitals, and a lack of capability in conducting nucleic acid tests in medical institutions in Harbin, it said.

All health authorities and medical institutions across the country are required to learn lessons from this.

All localities should improve management to detect, report, isolate and treat infections as early as possible, and provide support in policies, funds, human resources and materials to help medical institutions improve testing capacity and efficiency, the release said.

In a separate circular on Friday, the State Council also called for adopting strict measures to minimize possible infections in hospitals.

Hospitals should draft more detailed measures to curb infections. Fever clinics－the first place to encounter possible COVID-19 patients－must shoulder the responsibility of early reporting, early diagnosis and early quarantine, and transfer patients to designated hospitals in a timely manner, it said.

Meanwhile, Hubei, the nation's hardest-hit province, on Friday announced the lowering of its emergency response level from the highest to the second level from Saturday, after the province reported no new infections for 27 consecutive days.

A total of 82,874 infections had been reported on the Chinese mainland as of Thursday, with 4,633 deaths. Among them, Hubei province registered 68,128 infections and 4,512 deaths, according to the National Health Commission.

Yang Yunyan, vice-governor of Hubei, said on Friday that people were encouraged to avoid mass gatherings and indoor recreational facilities would remain closed.

Wang Xiaodong and Liu Kun contributed to this story.