https://apnews.com/692807a012fb41e9d4c4cced67422b9c

More than 8.1 million people in the U.S. have turned their iPhones and Android devices into pandemic contact-tracing tools, but it hasn't been of much use when their neighbors, classmates and coworkers aren't on the same system.

Apple and Google co-created “exposure notification" technology to alert phone users if they spent time near someone who tests positive for the coronavirus, so they know to get tested, too.