Quarantining is a significant interference with rights, which is why it is only recommended to be done under the advisement of health professionals. Using tech and data to do this can be particularly problematic.
Considering the billions of people who have smart phones generally use apps on these devices, it's possible to reach people and draw extensive data from their devices.
Telecommunications firms, including mobile operators, have extensive data on their customers, including location and contact data -- they and governments are keen to exploit this data.