Cedar Rapids wastewater samples show higher COVID concentration in recent weeks

CEDAR RAPIDS — Cedar Rapids’ wastewater may indicate the novel coronavirus spread is more pronounced than testing rates show.

Since this past summer, the city of Cedar Rapids has been testing its wastewater as part of a national study that aims to track the spread of the novel coronavirus and its variants.

Until now, coronavirus detection has typically correlated with data from Linn County Public Health on latest infection rates among residents. However, in recent weeks, normalized virus concentration in the wastewater is “more pronounced than the number of cases indicated by Linn County Public Health,” according to Cedar Rapids Utilities Director Roy Hesemann

“This could imply there are a higher number of COVID cases in our community than reported to Linn County Public Health, but we do not know this for certain,“ Hesemann said in a statement.

The rate of normalized coronavirus concentration has increased exponentially over the past month as new COVID-19 cases have risen locally and across the state, reaching levels not seen since December 2020. Normalized coronavirus concentration is a value derived by adjusting for level of industrial waste dilution from samples taken at the Water Pollution Control Facility.

On Dec. 6, it reached a high of 2,037,320 copies per liter of sewage before dipping back to 1,583,942 copies Dec. 13.

By comparison, Nov. 8 samples showed 296,214 copies per liter of sewage. The first sample taken on June 7 yielded 56,638 copies per liter of sewage.

As of Tuesday, there are 3,470 COVID-19 cases as well as 70 hospitalizations in Linn County, according to local public health officials. The seven-day average for new cases is about 138, an increase from the seven-day average of 80 reported two months ago by Linn County Public Health.

Since this past June, Cedar Rapids and other municipalities across the country have been participating in a national study by sampling sewage to understand the extent of the coronavirus’ presence in those communities. By doing so, researchers hope to generate more accurate public health responses in the next phase of the COVID-19 pandemic.

The study, which monitors sewage from more than 100 million Americans, is led by the Boston-based wastewater epidemiology company Biobot Analytics in partnership with federal health officials. Des Moines also is participating in the federal study.

Biobot Analytics said in a statement that as coronavirus variants continue to appear and COVID-19 testing fatigue increases nationwide, virus monitoring through wastewater sampling can help complement clinical testing.

Nationwide, normalized coronavirus concentration has continued to increase in the past month, reaching 1,297.8 copies per milliliter of sewage, or 33.9 cases per 100,000 people, as of Dec. 3. As of Dec. 8, the country reached 1,568.2 copies per milliliter of sewage, according to Biobot Analytics.

The University of Iowa is also piloting a program to test wastewater on its Iowa City campus to better understand coronavirus clusters among the student population. Sampling began this past February in sewage pipes beneath two residence halls, Mayflower and Daum.

UI Facilities Management launched the program in partnership with Engie North America, the university's private utilities operator; Student Health; University Housing and Dining; the College of Public Health; and the State Hygienic Lab.

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