The wife, however, has a job that involves buying food from markets and delivering it to restaurants and homes in the city.

A residential compound she visited on June 12 has been mentioned in the travel histories of four other confirmed cases.

Another of the infections was a 31-year-old woman who works at the same supermarket as the unnamed wife, while a fourth was a 47-year-old food delivery worker in the city’s Chaoyang district.

The two remaining cases were a 32-year-old man and a 39-year-old woman, who had both visited the CapitaMall Grand Canyon shopping centre in Beijing’s Fengtai district.

The mall has been temporarily closed pending testing of local residents and shop workers.

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Despite the apparently unconnected cases, Feng Zijian, deputy director of the Chinese Centre for Disease Control and Prevention, said the outbreak in Beijing was under control.

“By analysing the number of infections, onset of symptoms and source of infection, we can see the [outbreak] among those who had direct exposure to Xinfadi is coming to an end,” he said in an interview on state television on Monday night.

“The new cases were mostly down to community spread by those who had been exposed to the market, but the level of transmission is very low.”

The authorities’ rapid response to the Xinfadi cluster had been key to containing it, Feng said.

“The Beijing outbreak was discovered very early and the strong control measures have effectively curbed the spread of the disease,” he said.

Investigators were, however, still trying to determine how the market became a transmission hub for the coronavirus, he said.