Contact tracing in Alabama is starting to spread.
The GuideSafe Exposure Notification app notifies people about possible exposure to the coronavirus. The Alabama version used to only work for those who downloaded that state's version. Thursday it joined a larger network of 13 states and Washington D.C.
The app uses Bluetooth to signal if two cell phones are within 6 feet of each other for more than 15 minutes. If one user later tests positive for COVID-19, they report it to the app, which then notifies those who had been close by.