LANSING, Mich. (AP) — Michigan on Monday launched the statewide rollout of a voluntary, free coronavirus app that notifies users if they have potentially been in close contact with infected people.

The announcement came more than three weeks after the state began piloting the technology in Ingham County, including at Michigan State University. More than 46,000 people downloaded MI COVID Alert onto their smartphones.

State Health and Human Services Director Robert Gordon urged all Michiganders to follow suit, especially as COVID-19 cases and related hospitalizations have surged after an initial wave subsided last spring.

“I would encourage folks — try it out, put it on your phone. I think you'll see that it's free, it's easy, it doesn't gob up a lot of battery,” he told The Associated Press. “Once you're using it, then you get your friends and family to use it, too. If you do that, as a group you're going to be a little bit safer.”

Those testing positive for the virus are given a PIN by contact tracers that allows them to share their result anonymously on the app, which uses Bluetooth technology and randomly generated phone codes to track people's locations. Other app users who possibly were within 6 feet (1.8 meters) of infected people for at least 15 minutes are notified and urged to monitor for symptoms, be tested and self-isolate. They are not told who tested positive.

Other states have launched similar apps, including New York, New Jersey, Virginia, Arizona and Alabama.

The latest average positivity rate in Michigan is 10.45%, up from 5.33% two weeks ago. State health departments are calculating positivity rates differently across the country, but for Michigan The Associated Press calculates the rate by dividing new cases by test specimens using data from The COVID Tracking Project.

The seven-day average of daily new cases in Michigan has nearly doubled over the past two weeks from 2,356 to 4,514. The seven-day average of daily deaths has increased from 29 to 35 over the same period. Deaths remain well below the April peak but have been increasing for weeks.

Case rates continue to be particularly high in the Upper Peninsula. Five counties there have had the most new cases per capita in the past half month.

Beaumont Health, the state's largest health care system, reinstated patient visitor restrictions at three of its eight Detroit-area hospitals, effective Tuesday.

“We’ve had a notable rise in COVID-19 cases in metro Detroit,” said Dr. Nick Gilpin, medical director of infection prevention and epidemiology. “Community positivity rates have jumped to 8-11% in the area. Last spring, we took care of the most COVID-19 patients in the state and we know that taking difficult steps like restricting visitors will help us keep our patients and our staff safe.”

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