COVID-19 infection levels in Macomb Co. sewage 'dropping sharply,' officials say

Hayley Harding
The Detroit News

The level of COVID-19 infection showing up in sanitary sewage tests is "dropping sharply" in Macomb County, officials say, a potential indicator that the spread of the virus there is beginning to slow.

Lab tests, conducted from samples taken from wastewater in the seven sewage districts covering Clinton Township, show that the level of COVID-19 spiked Dec. 28, when it was at the highest level since the team started tracking it in August 2020. Samples from more recently, taken on Jan. 4, Jan. 9 and Jan. 11, show a decline.

In a Tuesday news release, Macomb County Public Works Commissioner Candice Miller said Clinton Township has been "quite an accurate reflection in Macomb County because of its size and demographics."

Workers pull sewage in January 2021 from a sampling location on Union Lake Road in Clinton Township.

“For the past few months, we’ve all been inundated with troubling and grim news reports involving COVID, particularly the highly-contagious omicron variant," Miller said. "The latest sewage-testing data that we have reviewed offers reason for optimism that infection rates have not only leveled off, but that infections are dropping significantly.”

The results are shared with the Macomb County Health Department. Experts say sewage testing is usually ahead of reported cases by a week or two.

Michigan is in a surge of COVID cases that has strained hospitals and made it difficult to find tests.

According to the Michigan Department of Health and Human Services, the virus is shed in feces for several weeks, both before people are sick as well as in those who aren't showing symptoms. 

MDHHS has been testing wastewater around the state for COVID-19 since 2020 through local projects. Monitoring can be important, the state says on its webpage, especially when testing rates are lower.

Wastewater testing can be used to alert local health leaders and recommend additional restrictions if needed.

Testing is showing a decline in some other places as well. Dr. Russell Faust, medical director for Oakland County, said the county also is beginning to see levels of virus in its water system drop after several weeks of high numbers.

Wayne County officials on Tuesday could not immediately provide information on the COVID levels in its wastewater samples.

Oakland County does their testing differently than some other teams by looking primarily at places like college dorms and long-term care facilities, Faust said. It's a more targeted approach than looking at the wastewater for a city or county, but it's helped his team to limit infections by testing those living in a specific building and quarantining those who are sick.

"It's an enormous benefit," Faust said. "We've used it to prevent an outbreak, and we've done that multiple times now."

There is value in looking at both sets of data, he said. The Centers for Disease Control and Prevention hasn't established a protocol for testing across the board yet because testing is new, but being able to know what is coming can be helpful, he said. 

Especially with home testing, not every positive case will be reported to the county or state, Faust said. But the ability to accurately gauge what comes next is helpful in studying the spread of COVID and will benefit the study of other disease as well.

"We're going to be monitoring for all sorts of things, like hepatitis," he said. "From there, if you see an uptick, you can monitor more targeted groups. It's a great model moving forward."

Twitter: @Hayley__Harding