Wuhan, the central Chinese city, will test its entire 11 million population within the coming days, after the first new cases of coronavirus were reported since it's strict lockdown was lifted.

On Monday, the municipal authorities issued a document from Wuhan's anti-virus teams in all districts to submit detailed plans by today on how they will test their residents to see if they have contracted the novel coronavirus, according to Chinese state-owned media outlet. Testing vulnerable groups and areas such as residential compounds should be prioritized by the plans, the document is cited as saying.

In response to the outbreak, Wuhan authorities will conduct nucleic acid testing across the city over a 10-day period. According to the document, the tests should give priority to people like those living in older compounds or densely packed residential buildings, or people originally from outside Wuhan who are more likely to travel between different places. How the department plans to satisfy the huge volume of test kits required is unclear.

Nucleic acid testing works by detecting the genetic code of the virus and may be more effective in detecting the infection, especially in the early stages, than testing the immune response of a body, although the latter is easier to perform.

The directive came after local authorities in Wuhan reported that six new local transmission cases were recorded within the Sanmin residential neighbourhood over the weekend. One of the cases being of an 89-year-old man who has not left the city since late January and was confirmed to have the virus on May 9. Before that, there were 20 confirmed cases in the man's compound that are thought to be the source of the man's infection. 

Five new cases were reported one day after, with all the asymptomatic patients (people who test positive for the virus and are capable of infecting others but do not show clinical signs) living in the same compound.

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

Even after Wuhan lifted its lockdown in early April, some stringent public health measures remain in place, including requiring residents to have their temperatures were taken and community workers scanning their telephone "health codes" when entering or coming out of their compounds.

The ambitious plan to test everyone in Wuhan highlights China's anxiety over a virus resurgence, after China's northeastern city Shulan, bordering North Korea, was partially locked down after 11 new infections were found. Many cities in China still do not allow the operation of the cinemas and bars, and there are still severe restrictions on social gatherings. Face masks are required for public transportation and for entering shops and public amenities.