A new Bluetooth-enabled mobile app will give Minnesotans with COVID-19 the ability to anonymously notify close contacts who they might have exposed to the infectious disease.

Gov. Tim Walz unveiled COVIDaware MN on Monday and urged Minnesotans to use the app to slow the spread of the pandemic that has caused at least 3,265 deaths and more than 276,500 lab-confirmed infections in the state.

"COVIDaware MN gives our state a powerful and anonymous new tool to alert others we've had close contact with — even people we don't know — and slow the spread of COVID-19," Walz said. Download information is at covidawaremn.com.

The app is based on public health research indicating that most transmissions of the novel coronavirus that causes COVID-19 occur when people have spent 15 minutes within 6 feet of one another. The app uses Bluetooth signal strength between devices to track whether the length and proximity of interactions were long enough to present an exposure risk.

State infectious disease director Kris Ehresmann said the app could be particularly useful given the surge in COVID-19 cases that is making it hard for state and local contact tracers to interview all of the people who have been infected and identify the contacts they might have exposed.

Minnesota's pandemic totals included 24 COVID-19 deaths and 6,353 infections reported Monday. The state also reported 1,778 Minnesota hospital beds were filled with COVID-19 patients, including 364 who needed intensive care.

The app can identify close contacts that people forgot or didn't know in the first place, Ehresmann said. "Typically, we have to rely on a person remembering who they may have been in contact with and the places that they visited while they were infectious. And oftentimes that's difficult and sometimes people have been in a situation in which they can't remember."

While the technology has existed for months on Apple and Google mobile platforms, Minnesota leaders hesitated to use it because of privacy concerns, and they emphasized that COVIDaware neither collects nor distributes personal identification. Users are identified by random and rotating ID numbers and can choose whether to anonymously alert recent close contacts of their viral exposure risks.

Only users of the app will be able to anonymously notify one another of exposure risks, and Minnesota IT Services Commissioner Tarek Tomes said the notification will come with only a time range for exposure and won't provide any location information.

"If communities are willing to adopt the app, use it, report positive test results, and follow health recommendations when notified of exposure," he said, "this app can help us return to many of the activities we miss so much and save lives."

More than a dozen states now use the technology, with many unveiling similar COVID-19 apps in recent weeks. Minnesota is one of multiple states using the app developed by the nonprofit PathCheck Foundation, which uses an open-source platform.

Making the code freely available provides extra assurance that data isn't being collected by the app, which is important given some mistrust in the community about whether companies are surreptitiously collecting personal information, said Shashi Shekhar, a University of Minnesota computer science professor who has studied the use of these apps in the pandemic.

"It's a pull-in app, which means the data can come to your smartphone but nothing of value leaves your smartphone," he said. "The only thing that leaves your phone is a random number, which cannot be traced back to the phone that generated it."

North Dakota was an early adopter of the technology last spring, converting an app designed to link fans of North Dakota State Bison football into Care19 Alert.

As in many states, the promise has been hampered by slow uptake. In North Dakota, fewer than 5% of people have used the app. And even among users who end up with COVID-19, some don't opt to anonymously notify close contacts of their exposure risks.

Other limitations include that the app tracks distance between devices, not people, and doesn't differentiate when people are separated by windows or barriers that could prevent viral transmission.

Adoption has been far broader in Asia and Europe. However, Tomes said a similar app in Colorado gained 1 million users in the two weeks after it was unveiled, and that an Oxford University study showed that as little as 15% adoption in a community can have a positive impact.

To prevent false reports, the app requires users to receive codes from local and state public health contact tracers that verify they received formal positive test results.

Ehresmann said contact tracers are busy but will have time to forward these codes quickly because they can reach people by phone, e-mail or text.

State health officials said they would promote the app in communities that are likely to use it, such as college campuses. Tomes said the app works better when used with higher frequency in individual communities, rather than sporadically across the state.

In Minnesota, the first attempt to confront COVID-19 with mobile device technology came from Bloomington-based HealthPartners with an app called SafeDistance. It used a crowdsourcing approach, allowing people to anonymously report when they had respiratory symptoms so that people living nearby could assess their risks.

Uptake was slowed because the app was not made available on the Google Play Store for Android phones. Developers at the time said they needed an endorsement from the Minnesota Department of Health to provide the app on that platform. State health officials had concerns that users would have a false sense of security if the app showed no illnesses in their immediate areas.

Walz accepted responsibility for slow rollout of the technology in Minnesota, saying he wanted all security and privacy concerns addressed first.

Jeremy Olson • 612-673-7744