ESCANABA — The detectable amount of the virus responsible for COVID-19 in Escanaba’s wastewater has continued to decline. If the trend continues, it’s possible the city could start the new year with lower than average infection rates.

According to the Sentinel Wastewater Epidemiology Evaluation Project, commonly known a “SWEEP,” the city’s most-recent wastewater sample, recorded Dec. 13, had more viral DNA than 50% of samples submitted to the program since Escanaba began tracking viral load through the project in late August of 2021.

While there is no real way to translate the amount of viral DNA found in the city’s sewer water to the number of active infections, the amount of viral load in wastewater reaching the 50% percentile suggests the rate of infections has normalized.

The 15-day trend suggests the viral load is continuing to decrease at a rate of between -100% and -999% — based on categorical ranges of exponential decay reported by SWEEP — as of Dec. 16. While the 15-day trends give a general picture of COVID-19 infections in Escanaba, there are delays in data reporting, and, by its nature, the system relies heavily on past data that may or may not be accurate.

For example, the samples submitted Nov. 8 and Nov. 15 had more viral DNA than 94% and 97% of all Escanaba samples, respectively. The Nov. 21 sample, however, was only reported as having a viral load greater than 6% of samples, with the following sample from Nov. 29 jumping back up to the 61st percentile.

While it is theoretically possible to have a 91% drop in viral load in a single week, it’s more likely there was an error in the data, which translated to a significant drop in the 15-day trend reported on Nov. 25 and then a rise in the trend reported for Dec. 2.

Still, when the Nov. 21 sample is accounted for, the city appears to be following a similar pattern to what was seen following the city’s highest recored spike in viral load, which took place in January of 2022. At that time, just over 40 copies of the viral gene were detected per 100mL of wastewater for three samples — fractionally more than were detected in November of this year, during the second-highest spike on record.

According to SWEEP, the 2022 spike in viral detection coincided with the highest number of cases reported for the city to the Michigan Department of Health and Human Services, with more than 350 cases per 100,000 people. Despite the nearly-identical viral load, only about 60 cases per 100,000 people were reported to MDHHS in November, which may be due to the shift to home testing.

By May of 2022 the number of cases reported to MDHHS dropped to levels below SWEEP’s reporting threshold and viral gene copies in wastewater dropped to some of the city’s lowest levels.

It is important to note that 2022’s spike ended just as people were beginning to enjoy warmer weather and spend more time outside — naturally social distancing. Any downward trend could be negated by colder temperatures and holiday festivities opening up opportunities for people to gather indoors and spread the virus.

If the holidays and cold weather don’t derail the trend, it’s possible the city could see some of its lowest reported viral load in January and early February, coinciding with very low infection rates.