So now we are in the middle of this pandemic. In the face of this, Google and Apple has joined forces to supply contact tracing. They will be releasing software to automatically and autonomously log all the people you have been in contact with. It uses Bluetooth to collect (encrypted) codes but it doesn’t know the identity of the person. The codes stay on your phone while you remain anonymous.
Apps can be built on the API they make that can do what needs to be done with the codes but you will have to give permissions. Contact tracing is used to try to keep coronavirus at bay. This will help find those who are positive stay quarantined during their contagious period and find those they have contacted before they were symptomatic.
Having Apple and Google on this, will ensure their respective OS systems can be ready for this. They have only built a way to collect and make alerts. It is up to healthcare/governments to build the app to handle the information.