California has launched a new cellphone app, CA Notify, designed to alert people if they have been exposed to someone who has tested positive for COVID-19.

In a news release, the state said CA Notify users who test positive for the virus will receive a text message from the California Department of Public Health with a code that they can plug into their cellphones. The code will trigger an alert sent to other CA Notify users who have been within 6 feet of the person who tested positive for 15 minutes or more in the previous two weeks.

The state said the app uses Bluetooth technology to exchange random codes between phones without collecting location data or revealing either user’s identity.

California residents can download the free CA Notify app to their iPhones or Android-based cellphones from the Google Play Store.

CA Notify was developed by the state in partnership with Google and Apple, and tested in a pilot program for students, staff and faculty at University of California campuses in San Diego and San Francisco. The university system expanded the pilot to five other campuses in mid-November and now estimates that more than 250,000 people are now utilizing the application.

“Throughout this pandemic we have tapped California’s talent pool to fight this virus and that includes working with tech innovators like Apple and Google,” said Gov. Gavin Newsom. “CA Notify will help slow the spread by alerting those who opt in to receive an alert if they’ve come into contact with someone who has tested positive.”

Newsom said the process “is private, anonymous and secure, and is one of the many tools in the state’s data-driven approach to help reduce the spread” of the virus.

Dr. Mark Ghaly, secretary of Health and Human Service, said the app would accelerate how quickly people get notified of a possible exposure to COVID-19, allowing them to make informed decisions about testing and possible quarantine.

“When combined with other actions like wearing masks and physical distancing, CA Notify can help curb the transmission of COVID-19,” Ghaly said.

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