In-Depth: CA Notify system deemed 'successful'

App alerts help with COVID-19 contact tracing
Posted at 6:08 AM, Apr 22, 2021
and last updated 2021-04-22 13:05:48-04

SAN DIEGO (KGTV) - A smartphone-based system to help with contract tracing for COVID-19 has been called a "success" by state health leaders after 10 million people signed up for it in the first four months.

The California Department of Public Health launched "CA Notify" on December 10. They estimate 1 in 4 California residents has either downloaded the app or activated it on their phone. That accounts for 39% of all smartphone users in the state.

The app uses Bluetooth technology to tell when your phone has been within 6 feet of another user's phone for more than 15 minutes. If that person tells the system they have tested positive for COVID-19, you get an alert.

"It's very clear that it's been successful," says Dr. Christopher Longhurst from UC San Diego.

The La Jolla-based campus helped develop the app and launched a pilot program to test it in September.

"Our early estimates are that we've avoided 1000s If not 10s of 1000s of COVID infections," Dr. Longhurst says.

CDPH officials say there's no way to get an actual number of how many cases were averted, and privacy laws prohibit them from tracking the exact number of alerts the system sent out.

But, each alert comes with a link to click for more information. CDPH officials tell ABC 10News that the link has been clicked more than 110,000 times.

Meanwhile, they say this form of phone-based contact tracing was nearly twice as effective as regular contact tracing.

In a statement to ABC 10News, CDPH officials explained:

"an average of 4.1 exposure notification alerts are sent out to potentially exposed users for every COVID-19-positive user who chooses to alert other users by submitting a verification code into the CA Notify system. That is approximately twice the number of contacts (2.1, on average) elicited from COVID-19 infected individuals during traditional contact tracing activities in California, potentially indicating the expanded reach of the CA Notify technology in alerting exposed contacts who are otherwise unknown to infected individuals."

Dr. Longhurst says that this technology helps identify close-contact people outside of a person's usual social or family circle.

"Contact tracing does a great job of picking up your family members and housemates. But it really falls apart when you're thinking about the person who was seated on the bus next to you or the person in the restaurant at the table next to you that you didn't know," he says.

"That's where this technology we think has been particularly effective is for getting those exposure notifications to people who otherwise never would have been traced with traditional contact tracing."

Dr. Longhurst says the system will shut down when the Pandemic is over. But UC San Diego is under contract to do an analysis on how effective it was. They're also looking at ways this technology could be helpful with future outbreaks or other respiratory diseases like the flu.

In the meantime, the state will continue to update the program as new research comes out on COVID-19 and as the CDC updates its recommendations for contact tracing.

Dr. Longhurst says people should keep using the system until the Pandemic ends.

"The fact that we have almost one in three Californians with a smartphone using the system is terrific. But there's still two in three that aren't using the system," he says.