Across Utah, more attention is being put on sewage than ever before. Since the spring, the Utah Department of Environmental Quality has been tracking the spread of COVID-19 in communities by surveying wastewater samples. Last week, Moab’s sample showed the highest spike yet of COVID-19 although no spike in documented confirmed cases has registered locally, leading to speculation by health officials that the high rates are the result of increased tourism.
The Utah Department of Environmental Quality has expanded its study of community sewage to 43 facilities around the state, representing about 80% of Utah’s population. The wastewater influent tests measure virus gene copies, compared to how many people a wastewater plant serves daily.
On Sept. 9, two days after Labor Day, a test sample was taken from the Moab Reclamation Facility. The sample tested showed 200 million gene copies per person per day, over 10 times greater than the highest level recorded in August. Previous spikes were recorded on May 6 (82 MGC/person/day) and on July 1 (130 MGC/person/day).
“It's our suspicion, but still speculation, that we're seeing these higher levels of COVID in our wastewater because of the transient population coming in— tourists—using our wastewater facilities,” said Orion Rogers, the environmental health director for the Southeast Utah Health Department.
Moab saw thousands of tourists flock to the area over Labor Day weekend, both to the local national and state parks and to the town itself. While confirmed COVID-19 cases remain low in Grand County, the tests show an influx in possibly infectious cases over the busy holiday weekend.
“Moab is, unfortunately, not alone in seeing a big increase with the latest sample. We're seeing this in a number of places across the state,” said Nathan LaCross, an epidemiologist from the Utah Department of Health. “And of course, we're seeing an increase in cases as well. So both of those things are concerning to us.”
Officials cautioned assuming too much in a single data point, however.
“We'd like to see two samples before we are confident that there's really a change, but that is a big jump,” said Erica Gaddis, the director of the Division of Water Quality at the Utah Department of Environmental Quality.
Cases Rising Statewide
“There are so many different factors that can influence how much RNA (viral genetic material) we end up detecting that it does complicate the interpretation,” LaCross said.
Temperature, storm runoff, wastewater transit times and other factors can all cause variability in how much viral material a lab is able to detect in a given sample.
Thus far, however, the efficacy of sewage monitoring seems to be proving out.
“In Salt Lake County, the Salt Lake City treatment plants saw a steady decline in wastewater coronavirus data starting in late June. That matched up with declining case counts around the same time,” explained Gaddis. “Right now we're seeing a jump in Utah County that corresponds with the increase that you've seen in the papers.”
Utah County currently has a steep increase in cases, with reports showing 200 or more new cases on several recent days. There were 299 new cases reported on Sept. 12, the highest so far for the county.
Statewide, the cases are growing again after a “plateau” period, with the Utah Department of Health reporting a steep growing curve since September 8.
Rural areas, in general, seem to be more protected from sharp increases of confirmed cases.
“We’ve had a number of facilities that have consistently not detected the virus and that's been reassuring to some of those rural areas, Daggett County being one,” said Gaddis.
She went on to say that Fillmore City and Gunnison City also showed no detection of viral RNA, perhaps because people are naturally socially distanced or the precautions they are taking are effective.
Evidence supports mask mandates
Even as confirmed cases are rising again around Utah, fewer people are coming to emergency rooms and outpatient clinics with COVID-like symptoms. Although these serious impacts tend to lag behind new cases, studies show that mask mandates may be reducing the number of severe and symptomatic cases.
According to a new article in the New England Journal of Medicine, masks may prevent not only the likelihood of infections from airborne diseases but also the severity of symptoms. Similarly, a study in The Lancet shows that the size of the viral load a person is exposed to is a predictor of how bad the infection will be. Masks reduce the viral load by absorbing virus-carrying water droplets that would otherwise travel through the air and therefore may mitigate the prevalence and severity of our current pandemic.
Grand County’s public mask mandate and a naturally less dense population could be why COVID-19 infections in Grand County have remained low.
“Our community has done a really good job,” said Rogers. “We closed down before a lot of other places and our community started taking it seriously a lot sooner.”