According to Xinhua, "close contact" includes people who work together, share a classroom or live in the same house, as well as medical professionals working with patients, and passengers on mass transit. If the app determines a user has been in close proximity to someone who has or is showing symptoms of the virus, they will be instructed to stay at home.

Xinhua has not disclosed exactly how the government-developed app works, nor how it determines the risk of exposure. However, the news agency reports that it has received support from several government agencies including the National Health Commission, the Ministry of Transport, China Railway and the Civil Aviation Administration of China to ensure "accurate, reliable and authoritative data."

The app's requirement for ID numbers as raised some concerns with privacy critics -- the Chinese government is well-known for conducting high levels of surveillance on its citizens. Others, however, maintain that stemming the spread of the virus -- so far responsible for more than 1,000 deaths -- outweighs the need for individual privacy.