New accounting fuels hope that coronavirus is better contained in Michigan

Michigan has changed how it reports coronavirus testing, revealing that the state is likely farther along on the curve than believed.

Michigan public health officials have altered how they report positive coronavirus tests in the state, changes that show fewer people have been infected in recent weeks than previously reported.

The change, announced this weekend, doesn’t not lower the number of confirmed coronavirus cases, which rose by 202 on Sunday to 54,881. But it shows the percentage of people who have tested positive for an active infection has fallen further than earlier reported.

Before the change, the state reported that 7.7 percent tests were positive in the last week. With the change, that percentage falls to 6.7 percent, with the most recent day reported, Friday, at 4.2 percent.

A lower rate of positive tests is good news because it suggests testing is more widespread and the virus is better contained.

Michigan, like many states, had until now combined the number of people who tested positive for an active infection with those for whose tests indicated they had previously contracted COVID-19.

The latter test, called a serology or antibody test, detects antibodies tied to previous exposure to the virus and suggests the person has recovered and is not likely to spread the virus. 

Here’s why it’s important: One of the metrics Gov. Gretchen Whitmer has used to gradually reopen the economy is whether the percent of people who test positive for COVID-19 steadily falls and remains below 10 percent. Michigan had seen positive tests fall for weeks but, on May 13, the state reported that it had spiked to 13.2 percent.

It turns out that jump was based on the inclusion of nearly 6,500 serology tests, of which 35 percent were positive. The actual positive test rate for people with an active infection that day was 5.3 percent, the new numbers show.

By combining the results from two tests, it can make it look like more tests are being conducted and widespread testing has been a goal to reopen more of the economy. But to control the spread of the virus, public health officials need to be able to accurately track who currently has the virus, separate from those who have recovered. 

Combining results from those two tests led epidemiologists to recently criticize the Centers for Disease Control and Prevention, which gathers COVID-19 data from the states and was likewise combining the tests in its reporting. In addition to Michigan, health officials in Virginia, Texas, Georgia and Vermont also said they would separate the two tests.

Michigan made the change in its daily data release Saturday and sent a press release later Saturday during the holiday weekend explaining the change.

“Accuracy and transparency are paramount as we continue to respond to this pandemic,” said Dr. Joneigh Khaldun, chief medical executive and chief deputy for health. “We continue to expand and improve data reporting to make sure the public understands where their community stands with the COVID-19 outbreak.”

On Sunday, the state reported the fewest number of deaths since March, with just 5. The numbers have steadily fallen since the peak of the pandemic in late March and early April but weekend reporting numbers have typically been lower than weekday reports.

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D. Phillips
Mon, 05/25/2020 - 7:26pm

I'm assuming there's a typo in the first sentence of the second paragraph: "The change, announced this weekend, DOESN'T NOT lower the number...."

Robert George
Mon, 05/25/2020 - 8:19pm

Sorry, but "percentage of people testing positive" is a pretty poor metric to use for reopening. You are literally depending on people who incorrectly believe they have the disease to tell you things are getting better. The best metric is likely hospitalizations... at least it was when we still wanted to "flatten the curve".

Mon, 05/25/2020 - 10:40pm

Dr. Khaldun rocks. She has not sugar coated anything.

Tue, 05/26/2020 - 8:48am

Anything to extend the unconstitutional power grab, I guess.

Tue, 05/26/2020 - 9:58am

If masking and social distancing don't make much of a difference, then the U.P. should be fine. If it does make a difference, look for U.P. numbers to spike within the next couple of weeks. The number of people in U.P. stores not wearing masks, to include employees, this weekend was a bit shocking.

Tue, 05/26/2020 - 10:40am

The entire area of CVD19 is full of unknowns. This makes it very easy to use any stat you come up with to get the effect, recommendation or the policy you want. Both sides are doing it, those who are inclined to regulating especially so, and are betting that the public will forget, confuse or forgive the number of very expensive and often ineffective "solutions" imposed, and be judged by the fact that they "did something" and things seemingly got better not by whether it actually and scientifically worked.