SAN FRANCISCO (CBS SF) — A new smartphone app is now available for Californians to let them know if they’ve been too close to someone who’s been infected with the coronavirus.

Announced earlier this week, the CA Notify app went live Thursday and uses a new smartphone feature called “exposure notifications” that users opt-in to receive.

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Californians can activate the tool in their iPhone settings or on Android phones by downloading the CA Notify app from the Google Play store after receiving a notification.

The app allows people who test positive for COVID-19 to anonymously inform people who have been in close proximity over the previous two weeks that they may have been exposed. It uses bluetooth technology to exchange so-called anonymous keys.

Earlier this week, Governor Gavin Newsom explained the app using an example of a conversation between Alice and Bob, and what happens after Alice tests positive for COVID.

“You receive a code via text from the California Department of Public Health, for CA Notify. If Alice consents for CA Notify to anonymously alert other users that she has likely been exposed in the last 14 days, then Bob gets notified,” said Newsom. “Fully automated, opt-in technology. Not contact tracing. Does not provide your personal information.”

Privacy experts tell KPIX a lot of thought went into this, and that federal HIPPA regulations will safeguard your medical information.

You must opt-in for exposure notifications for the app to work. The more people that do it, the better it will perform.

Oakland Mayor Libby Schaaf vouched for the app’s safety and privacy.

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“It’s super easy. I’ve done it,” said Schaaf. “I encourage everyone to turn on this notification tool, or to download it immediately. It is a lifesaver.”

San Jose residents Emily Howard and Joe Morton talked to KPIX about the app after it went live.

When asked if she trusted it, Howard replied, “I think so, yeah. I mean, Alexa is already listening to us when we say things, so…”

Both thought it sounded like a good idea.

“I mean, you need to know where your exposure’s coming from and I think the phone is the best way,” said Howard.

“Because usually now, you’re texting somebody like, ‘Hey I don’t feel well. You should go get tested.’ And now we’re all getting tested, said Morton. Everyone has concerns about Big Brother, but at this point health, I think, outweighs the concerns of privacy.”

Sixteen other states, plus Guam and Washington, D.C., have already made available the system co-created by Silicon Valley giants Apple and Google, though most residents of those places aren’t using it. The tool has been used on a pilot basis on University of California campuses to try to track virus cases.

The app’s launch comes as coronavirus cases are exploding in California and more than 80 percent of the state’s residents are under orders not to leave their homes for at least the next three weeks except for essential purposes.

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