Michigan artificially inflated its coronavirus testing numbers

May 26, 2020 at 2:19 pm
click to enlarge Michigan artificially inflated its coronavirus testing numbers

Gov. Gretchen Whitmer repeatedly boasted in May that the state is dramatically increasing the number of daily coronavirus tests, a key metric to reopening the economy.

“Widespread testing will give us the confidence that we know where COVID-19 is and that we’re able to prevent more community spread,” Whitmer said at a May 15 news conference. “Right now we’re seventh in the nation in terms of daily tests that are done.”

It turns out Michigan was artificially inflating its testing totals by combining two very different kinds of tests — those that identify an active infection and those that indicate past exposure, providing an inaccurate picture of the state’s testing capacity.

To reopen the economy, diagnostic testing is needed to identify outbreaks and contain them by providing a real-time picture of how many people currently have the coronavirus. Antibody testing, on the other hand, indicates a past exposure, rather than detecting a current infection.

By combining the diagnostic and antibody tests, Michigan was muddying key statistics that public health officials use to measure the scope of the outbreak and when it’s safe to reopen the economy.

On Friday, the Michigan Department of Health and Human Services (MDHHS) said it would no longer combine both types of tests following media reports about a handful of other states engaging in the misleading practice.

“Combining a test that is designed to detect current infection with a test that detects infection at some point in the past is just really confusing and muddies the water,” William Hanage, an epidemiology professor at Harvard University, told The Atlantic.

In a news release, the MDHHS acknowledged that “Michigan — along with some other states — has not separated data for diagnostic and serology tests.”

“Accuracy and transparency are paramount as we continue to respond to this pandemic,” Dr. Joneigh Khaldun, the state’s chief medical executive, says in the news release. “We continue to expand and improve data reporting to make sure the public understands where their community stands with the COVID-19 outbreak.”

About 12% of the total tests were for antibodies.

Whitmer has repeatedly said the state must be testing at least 15,000 people a day before she feels comfortable lifting more restrictions on her stay-at-home order. In mid-May, she boasted that the state was on track to reach its goal of 450,000 tests in May.

It’s not. Of the nearly 330,000 tests conducted in the first 22 days of May, more than 61,000 were antibody tests. The state was averaging 15,000 tests a day when MDHHS combined both types of tests. By removing antibody tests, the state is averaging nearly 12,200 tests a day in May.

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