Technology on Apple and Google phones in some states can notify you if you were close to someone who later tested positive for Covid-19. The alerts come via state health department apps that use Bluetooth technology to detect when you (or more precisely, your phone) has been in close contact with an infected person's phone.

Apps cannot keep you safe, but they let you know if you have been exposed and should take precautions, such as self-quarantining, after receiving an alert.

While the apps aren't available in every state, millions of people are signing up.  Health officials believe the alerts could be especially helpful in cases where an infected person has been in contact with strangers -- for example in a bus, train or checkout line -- who wouldn't otherwise know they were exposed.

Read the full article on CNN here.