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Michigan is undercounting COVID cases. At-home testing is one reason why

Over-the-counter rapid antigen tests allow people to get tested from home for COVID-19.
Wikimedia Commons
Over-the-counter rapid antigen tests allow people to get tested from home for COVID-19.

For Sam Phelps, it started with a sore throat and some aches. He took an at-home rapid COVID-19 test that came back positive.

A few days later, the Royal Oak resident took a more sensitive polymerase chain reaction, or PCR test, which was negative.

“I had a booster and so it seems like I had a very mild case," Phelps said. "But, yeah, I'm certain that I had COVID.”

Phelps says the rapid test was useful because it prompted him to isolate from others. To public health officials, however, his positive result likely remained invisible.

At-home rapid tests are surging in popularity. But the state isn't tracking results from many of those tests, leading to an undercount of cases.

Although Michigan tracks COVID tests done in labs and through official channels like schools and health care systems, residents are not required to report results from over-the-counter rapid tests, Michigan's Chief Medical Executive Dr. Natasha Bagdasarian said.

“Absolutely, we will be undercounting cases with the availability of at-home tests," Bagdasarian said.

Bagdasarian suggests people tell their doctors about a positive self test if they have comorbidities or severe symptoms.

And she says Michiganders should notify their local health departments if transmission occurred at a high risk place like a nursing home.

But that’s far from all cases.

At this stage, it’s more helpful to watch other metrics tracked by the state like hospital intakes and deaths, Bagdasarian said.

"This is no longer an isolated illness that's cropping up in a few hundred people," she said. "This is now something that is very prevalent in our communities and so what we are trying to do at the state level is to prevent severe outcomes and prevent death."

State data shows hospitals are strained as cases surge. Michigan is averaging more than 10,000 infections each day, according to numbers updated Tuesday. Most of those are confirmed cases from PCR tests over the previous week. But the more than 1,000 probable cases could include rapid tests done in labs.

"We can still paint a big picture of where we are in the pandemic, which is of course, not a good place right now," Bagdasarian said.

Ingham County Health Officer Linda Vail admits the state’s case numbers aren’t a full accounting. Still, she contends the speed and convenience of at-home testing outweighs the drawbacks.

"At least people are testing and they have options to, you know, test before going to a family gathering, test before travel," Vail said.

Cases have been undercounted since the pandemic began, Vail said. Some people struggled to get tests authorized. Others never got tested because they didn’t have symptoms.

Although case data is limited, Michigan scientists are monitoring wastewater for shedding virus. That allows officials to estimate how far COVID-19 is spreading in the population, including to people who never got tested.

Additionally, state officials are urging people who test positive with a rapid or PCR test to use the website tellyourcontacts.org to notify others they could have exposed. Results from that website are anonymous, however, and do not contribute to Michigan's case tallies, a Michigan health department spokeswoman said.

Debra Furr-Holden, an epidemiologist at Michigan State University, says Michigan needs comprehensive infection data that includes self tests.

Case data helps scientists track severity by calculating what percentage of cases result in illness or death. And Michigan's positivity rate — the percentage of tests that come back positive for the virus — will be skewed if some tests aren't counted.

"Knowledge is power and not being able to accurately estimate the extent of the problem only dampens our ability to mitigate it," Furr-Holden said. “People should be able to administer the tests, scan a QR code and enter in their results into a database that would feed up to their state.”

Washington, D.C.’s health department recently rolled out an online portal for reporting self tests. But such options are far from standard.

Accessible testing is key to taming the pandemic along with vaccinations and indoor masking, Bagdasarian said.

“Testing is one piece in this puzzle and can't be used alone," she said. "We have to use all of these strategies together.”

Many Americanssay they’ve struggled to buy testsamid high demand and steep prices.

Michigan’s health department promises to ease the problem by distributing free self tests through libraries. And President Joe Biden pledges to have the federal government mail a billion free at-home tests to those who request them.

Whether and how results from such tests will be tallied remains to be seen.

Sarah Lehr is a politics and civics reporter for WKAR News.
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