China has launched an app that lets its 1.4 billion citizens check if they've crossed paths with anyone infected with the Wuhan coronavirus.

The "Close Contact Detector" app was rolled out by the National Health Commission on Saturday.

Users put in their phone number, which is checked against government databases, and reveals if they've come within range of a patient.

The virus has killed more than than 1,000 people and infected more than 42,000 since it broke out in December.

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China has launched an app for people to check if they've crossed paths with anyone infected with the Wuhan coronavirus.

The "Close Contact Detector" app was rolled out by the National Health Commission on Saturday.

The app requires users to input their phone number, which is then used to track the person's past locations in relation to other app users.

"Close contact refers to someone who has come in close distance, with no effective protection, with confirmed cases, suspected cases or mild cases," the National Health Commission said.

The Commission said that on a flight, for example, passengers on the same row, and three rows in front and three behind, as an infected person are regarded as being in "close contact."

In this photo released by the Indonesian Foreign Ministry, Indonesians arriving from Wuhan, China, are sprayed with antiseptic at Hang Nadim Airport in Batam, Indonesia on Sunday, February 2, 2020. Indonesian Foreign Ministry via AP

The virus, which started in Wuhan in December, has killed more than 1,000 people and infected more than 42,000 globally, although the majority of cases are in the Hubei province of China.

This is not the first time that China has used its considerable surveillance resources and advanced technology in the quest to contain the Wuhan virus.

Drones that issue medical commands to citizens have been spotted over towns.

In one video, a drone can be heard telling an old lady: "You shouldn't walk about without wearing a mask."

A woman and a young boy in Wuhan, China. Getty Images

Chinese officials are monitoring the locations of those suspected to have contracted the virus and told to stay at home, and are catching those who break curfew via facial recognition cameras.

Reuters reported this month that the facial-recognition firm Megvii said it is testing a new "AI temperature measurement system" in Beijing that "detects temperature with thermal cameras and uses body and facial data to identify individuals."

Soldiers wear protective suits during the arrival of Brazilians repatriated from Wuhan, China, the epicenter of the coronavirus, at the Annapolis Air Force Base, in Anapolis city, Goias state, Brazil, Sunday, Feb. 9, 2020. Dozens of Brazilians landed early Sunday morning at the airbase in the Brazilian state of Goias, where they will spend the next 18 days in quarantine. Associated Press

Hong Kong-based technology lawyer Carolyn Bigg told the BBC the new app was a useful aide.

"From a Chinese perspective this is a really useful service for people. It's a really powerful tool that really shows the power of data being used for good," she said.

The app was made by the General Office of the State Council and China Electronics Technology Group Corporations (CETC.)

While the technology is being put to good use in this case, in one other, many residents of China have complained on social media that their compulsory face masks have made it impossible to unlock their phones with Face ID.