California launches Covid-19 exposure notification system.

In California, your smartphone can now alert you if you’ve been in contact with someone who has Covid-19. That’s if you opt in—the notification system, which became broadly available on Thursday, Dec. 10, and is known as CA Notify, requires users to enable certain settings in order to participate.

“This holds a lot of promise,” Gov. Gavin Newsom said at a news conference Monday, Dec. 7. “The more people that participate in it, the more that opt in, the more effective this program can be.”

On an iPhone, enabling the notifications involves navigating to the phone’s settings, and following the prompts under the “Exposure Notifications” tab. For Android, an app is available to download from the Google Play store.

The technology is the result of a partnership between Apple and Google that the two tech giants first announced in April. The system uses your phone’s Bluetooth capability to record instances in which your phone is within close range of another phone for longer than 15 minutes. If a user you’ve been close to tests positive for Covid-19, they will get a code from California’s Department of Public Health to put into the app. The app will then send you an anonymous notification, informing you that you’ve potentially been exposed to the virus.

The system doesn’t collect or share location data or other personal information.

“We are encouraging people to sign up for the app,” Karen Smith, public information officer for the Monterey County Health Department, told the Weekly via email.

California is the 18th state (plus Washington, D.C.) to use the technology from Apple and Google to release a contact tracing app, and the biggest in terms of population. Ultimately, the utility of the system will depend on the number of people who opt in and use it.