Gov. Gretchen Whitmer first learned the coronavirus had come to Michigan shortly after 8:49 p.m. March 10, with the confirmation of two cases in metro Detroit, internal emails show.
Since then, state officials have learned there already were likely 500 infections in Michigan at that time.
And nearly 10,000 people in Michigan were likely infected on March 24, when Whitmer issued her first stay-at-home order — more than five times the number of illnesses known at the time.
The difference: The estimates show the first day infected Michiganders experienced symptoms, rather than when tests confirmed they had the virus that has sickened some 50,000 state residents and killed nearly 5,000.
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Michigan has posted the symptoms estimates on its coronavirus database since mid-April.
And while the data do not contradict anything Whitmer or other government officials have said, they do offer an alternative way to visualize how and when the virus has spread throughout the state.
The symptoms data, for instance, show the virus was spreading well before the state’s infectious disease chief, Jim Collins, sent an email to state officials on March 10 announcing “Michigan has joined the ranks of all other great lakes states” with two positive tests in Oakland and Wayne counties.
By the time Michigan's infectious disease chief, Jim Collins, received word on March 10 of the state's first two confirmed COVID-19 cases, some 500 people in Michigan already were coming down with the illness. (Screenshot of email obtained by Bridge Magazine through Freedom of Information Act)
At least 13 people experienced symptoms as early as March 1, with nine of those in metro Detroit.
The data also show that new cases have dropped steadily since March 27, rather than April 3, when the state announced 1,953 positive tests.
Michigan receives the symptoms data after residents test positive and tell their physicians or test administrators when they first felt ill. That day is known as the “onset” date and is sent to state and local health officials, said Lynn Sutfin, a spokesperson for the Michigan Department of Health and Human Services.
New look at virus
COVID-19 cases in Michigan have fallen more steadily, for a longer period of time, according to records showing when people actually felt symptoms of the illness rather than when they got a positive test.
In cases when someone without symptoms has a positive test, like a front-line health care worker, the “onset” date is the day of the test, Sutfin said.
The takeaways from the data: Michigan is further along in its coronavirus fight than previously believed and Whitmer’s stay-at-home order had an almost immediate impact in slowing the curve.
The daily number of residents with symptoms has fallen steadily since March 27, three days after Whitmer’s order. The number of reported positive tests for coronavirus, meanwhile, rose for eight days after Whitmer’s order into early April.
Those trends continue into May: The average case count of symptoms data on May 8 was about 230 cases a day, less than half of 560 cases a day looking solely at the date a positive test was reported.
That indicates infections appear to be less widespread now. The records also would appear to confirm that, while cases are steadily declining statewide, there are stark differences between regions.
Southeast Michigan has seen infections fall precipitously for weeks while they have just hit an apparent peak in west and southwest Michigan.
Virus arc differs widely by region
Metro Detroit was hammered by COVID-19 cases in March but infections have been in decline for weeks while west Michigan saw its first substantial rise in cases in late April.