New Phone App Tells You If You’ve Been Around Someone With COVID
A new phone app will send you an alert if you have been near someone who tested positive for COVID-19.
It tells you after the fact so, it may not help you avoid getting the coronavirus. It will at least alert you to the exposure so you can seek medical attention sooner.
The alert works via Bluetooth and "remembers" what phones you have recently been in close proximity to.
When someone who uses the feature tests positive for coronavirus, he or she gets a PIN from a health official to enter into their phone. Any other phone that was nearby in the previous two weeks — usually within six feet or less, for at least 15 minutes — will get an alert telling the user to quarantine and notify a health provider.
The apps assess your risk on the strength of the Bluetooth signal (how close you were to the other person) and the duration of your contact with them. - KVIA
The feature is completely voluntary and can be turned on and off at the user's discretion. Though the number of users is huge and growing fast, not everyone will use it.
Therefore just because you haven't gotten an alert after being around others doesn't mean you haven't been exposed. You and the person who is positive both have to have the feature enabled. Privacy and user anonymity are assured, read more here.