Workers pull sewage samples recently in Clinton Township. Samples pulled from sites across Clinton Township show the COVID-19 infection rate is higher than numbers currently reported by state health officials.

Workers pull sewage samples recently in Clinton Township. Samples pulled from sites across Clinton Township show the COVID-19 infection rate is higher than numbers currently reported by state health officials.

Photo provided by Macomb County Public Works


Sewage testing indicates COVID numbers continue to climb

Macomb County sees 125% increase over 2 weeks

By: Alex Szwarc | Metro | Published March 23, 2021

MACOMB COUNTY – The Macomb County Public Works Office reports that March’s increase in COVID-19 infections in Macomb County are higher than clinical numbers show and will likely increase further.

That is based on automated sampling of sanitary sewage directed by the Public Works Office. 

A March 23 press release indicates that the number of county residents who have tested positive has increased 125% in the last two weeks, putting residents at a “very high risk level.” It notes that the jump in cases exceeds the statewide increase of 101% for the same period.

Using leading-edge technology, sewage testing for the presence of COVID-19 in the sanitary waste stream also reveals when and where an outbreak of clinically reported cases is likely to occur.

“The pulling of sewage samples, and subsequent laboratory tests to detect the level of the coronavirus, started as a pilot program in Clinton Township,” the release states. “The goal was to assist the Macomb County Health Department with the huge task of contact tracing and other efforts to reduce the spread of the highly infectious virus.”

Officials believe that in Macomb County, the number of official positive tests likely will continue to rise. 

“Testing shows the trend line of what’s coming about a week before, it’s a precursor,” Macomb County Public Works Commissioner Candice S. Miller said. “Unfortunately our testing is showing that COVID cases will continue to climb into next week.” 

In March, nearly 4,700 COVID-19 cases have been reported in Macomb County.

Sewage samples pulled from sites across Clinton Township show the rate of actual infection is higher than numbers currently reported by state health officials. 

“Laboratory testing of sewage to detect the coronavirus is considered more accurate in determining overall community infection because it includes sampling of waste shed by individuals who are already infected but who haven’t been tested,” the release states. “As some infected individuals await test results – or don’t get tested at all -- the data from testing of sewage provides a quicker and more thorough snapshot of infection in the population.”

The county notes that at one point last fall, analysis of lab results showed the level of COVID-19 in Clinton Township was approximately five times higher than what clinical reporting data showed.

The increase in cases comes at a time when vaccine eligibility in Michigan expanded March 22 to include all Michiganders age 50 and older, and to anyone age 16 and older with disabilities or medical conditions that put them at high risk of negative COVID-19 outcome. 

Beginning April 5, all Michiganders age 16 and up who were not previously eligible will become eligible to receive a vaccine.