UArizona says contact tracing app has reduced coronavirus cases by 12%

PHOENIX — A COVID-19 contact tracing app launched by the University of Arizona in August has reduced coronavirus transmission by 12%, according to university analysts.

“A 12% reduction in that transmission doesn’t just mean that you have a reduction in that next wave of cases but every subsequent wave of cases,” College of Public Health professor Kacey Ernst said in a press release. “If one in eight can benefit from this, that’s pretty good. It’s easy to use, and the benefit keeps increasing as more people use it.”

The COVID Watch Arizona app is fully anonymous and works by exchanging random codes between app users’ phones via Bluetooth when they are near each other instead of tracking users’ locations.

When someone tests positive for coronavirus, they can enter a verification code into the app, which then sends an alert to users who were near the infected person and may have been exposed.

The estimated reduction in spread is based on the app’s download rates, answers from infected individuals interviewed by the school’s manual contact tracers and the number of positive verification codes given out by Campus Health.

Nearly half of those interviewed said they had downloaded the app and 26% of those with the app said they had input the verification code to alert others.

“If 26% of COVID-positive app users entered a verification code into the app and 47% of the people they infected had the app and received the exposure alert, that would translate to about 12% of infected people receiving an exposure notification from the person who infected them,” the school said in the release.

If the 12% of infected people quarantined in enough time to stop the spread, the average number of people infected would drop.

Analysts noted that the 12% reduction could be lower or higher depending on if people chose to quarantine after receiving exposure alerts or if they didn’t have their phones with them when they were exposed.

Campus Health providers said more students are using the app because they like the anonymous features. Around 14,000 people on UArizona’s campus have downloaded the app, according to the university.

The university has been using the app in conjunction with human contact tracers in order to make sure everyone with a potential infection is notified.

The same app is also being used at Northern Arizona University.

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