Free tracking option from Google Maps:

If you have Google Timeline turned on, your phone can track your movements.  You can view “raw data” (export as kml formatted file) which will show the coordinates and time each time your phone is polled for its location.  I have noted that Timeline will actually show the locations which I visit, such as grocery stores and my pharmacy.

I could see that if you test positive for the COVID virus, you could generate the data so that it could be used to show the exact time and locations you were in prior days. Someone could feed this data, from multiple people, into a database to track hotspots.

This is a free tracking option from Google Maps, that anyone can turn on, and if they keep their smartphone with them, it continues to track. It works if you are in a car, or if you are walking around in a store or mall.