I mean I'm familiar with Tinder... even Citizen! Both apps tell you when people of specific interest, or even crimes, are happening in a close proximity to you!
And I hate to be cliche but when it comes to coronavirus, THERE'S AN APP FOR THAT!
According to 6abc, Pennsylvania plans to launch an app called "COVID ALERT PA" in September that will alert you when someone who has been exposed to coronavirus is in your area and were they are within your proximity so that you can avoid those locations.
Seem's a little exposing doesn't it? Well don't worry, the app will keep your identity private and doesn't track your location.