BEIJING--Wuhan reported its first cluster of coronavirus infections since a lockdown on the city, the epicenter of the outbreak in China, was lifted a month ago, stoking concerns of a wider resurgence.

The five new confirmed cases, all from the same residential compound, come amid efforts to ease restrictions across China as businesses restart and individuals get back to work.

“We must resolutely contain the risk of a rebound,” the health authority in Wuhan, a city with a population of about 11 million, said in a statement on Monday.

New confirmed cases reported in China since April have been low compared with the thousands every day in February, thanks to a nationwide regime of screening, testing and quarantine.

And Beijing said on Friday that cinemas, museums and other venues would gradually be reopened, though restrictions including mandatory reservations and a limit on numbers of visitors would be in place.

Meanwhile, some Shanghai night spots are open again and Walt Disney Co reopened its Shanghai Disneyland park to a reduced number of visitors.

All of the latest cases in Wuhan were previously classified as asymptomatic, people who test positive for the virus and are capable of infecting others but do not show clinical signs.

Hundreds of asymptomatic cases in Wuhan, which was released on April 8 from a months-long lockdown, are being monitored.

On average, the city has conducted about 47,000 nucleic acid tests each day since the lockdown was lifted, Reuters calculations based on reports by Wuhan’s health authority show.

China does not include asymptomatic cases in its overall tally of confirmed cases, now at 82,918, until they exhibit signs of infection. Mainland China has reported 4,633 deaths.

Wuhan plans to conduct nucleic acid testing over a period of 10 days, an internal document seen by Reuters showed and two sources familiar with the situation said, with every district told to submit a detailed testing plan by Tuesday.

Older and densely populated residential compounds and those with a concentration of migrant populations should be the focus of the testing, the document also showed.

New outbreaks in China in the past two months have mainly developed in residential compounds or hospitals, while the number of asymptomatic cases is not known, as these only appear on the radar when they show up positive during tests.

Wuhan’s health authority could not be immediately reached for comment outside of business hours.

‘WAR TIME’ MODE

As Wuhan reported new cases, Mi Feng, spokesman for China’s National Health Commission, said new infections over the past 14 days in seven provinces were being traced while cases involving clusters “were continuing to increase.”

The health authority called for stronger protocols at laboratories handling samples of coronavirus strains and human nucleic acid tests as well as in transporting them.

“We need to investigate and determine the origin of the infections and transmission routes,” Mi told a media briefing.

China’s northeastern province of Jilin, which on Saturday reported a cluster of infections in Shulan, reported three additional cases. Shulan has been marked a high-risk area, the only place in China now with that designation.

“We’re now in a ‘war-time’ mode,” said Jin Hua, the mayor of Shulan, which until the weekend had reported no local cases for more than 70 days.

Shulan has imposed a lockdown on its 600,000 residents since the weekend, with just one member of a household being allowed out each day to buy necessities.

One of the three cases confirmed in Jilin province on May 10 was from Shulan. The other two were uncovered through contact tracing of people who were in contact with earlier Shulan cases.

Nearby Liaoning and Heilongjiang provinces each reported one case, fueling worries of a regional resurgence.

A 70-year-old in Heilongjiang’s capital Harbin had tested negative seven times before results showed as positive.

Of the new cases, seven were in the northern region of Inner Mongolia and involved travelers from abroad.

Across China, the number of new asymptomatic coronavirus cases fell to 12 on May 10, compared with 20 a day earlier.