Hanwang, the facial-recognition company that has placed 2 million of its cameras at entrance gates across the world, started preparing for the coronavirus in early January.

Huang Lei, the company’s chief technical officer, said that even before the new virus was widely known about, he had begun to get requests from hospitals at the centre of the outbreak in Hubei province to update its software to recognise nurses wearing masks.

“We wouldn’t wait until something explodes to act. If three or five clients ask for the same thing . . . we’ll see that as important,” said Mr Huang, adding that its cameras previously only recognised people in masks half the time, compared with 99.5 percent accuracy for a full face image.