Thanks to a new feature in both iOS and Android, if you encounter someone who has been exposed to COVID-19, the phone will be able to alert you based on the person's location data, and that of others they have encountered. And if you're sick, it will enable medical professionals to track the path of infection through phone location data. It's called "contact tracing." The new feature has met with protest though, because Apple won't give governments all the information. It will also be a voluntary download. Leo says, though, that most people would likely download an app to track the path if it meant they could come out of self-isolation. But Leo says it's a good idea, even if only a small percentage of users adopt the app, it'll help flatten the curve.