[M T]

Singapore is now using an app that tracks people (from before being sick).  It was released on March 20.
  "Singapore says it will make its contact tracing tech freely available to developers"

Phones that have the app installed exchange short-distance Bluetooth signals when their users are near one another. Records of those encounters, including the duration, are stored in their respective phones for 21 days, according to the app’s frequently asked questions section. It added that location data is not collected. 

If a user is diagnosed with COVID-19, the respiratory illness caused by the coronavirus, they could allow Singapore’s health ministry to access their app data to identify people who had close contact with the infected individual.

South Korea is publishing the movements of people before they were diagnosed with the virus by retracing their steps using GPS phone tracking, credit card records, surveillance video and personal interviews with patients, the Washington Post reported earlier this month.

Israel has an app that can warn users if they’ve crossed paths with someone infected by the coronavirus.

[M T]

Singapore is now using an app that tracks people (from before being sick).  It was released on March 20.
  "Singapore says it will make its contact tracing tech freely available to developers"

Phones that have the app installed exchange short-distance Bluetooth signals when their users are near one another. Records of those encounters, including the duration, are stored in their respective phones for 21 days, according to the app’s frequently asked questions section. It added that location data is not collected. 

If a user is diagnosed with COVID-19, the respiratory illness caused by the coronavirus, they could allow Singapore’s health ministry to access their app data to identify people who had close contact with the infected individual.

South Korea is publishing the movements of people before they were diagnosed with the virus by retracing their steps using GPS phone tracking, credit card records, surveillance video and personal interviews with patients, the Washington Post reported earlier this month.

Israel has an app that can warn users if they’ve crossed paths with someone infected by the coronavirus.