Usually the first sign of COVID-19 is a fever, cough or maybe a sore throat and shortness of breath. But at Saint Joseph’s College in Standish, the first sign of a recent outbreak of the disease appeared in the school’s wastewater — surveillance wastewater testing tipped off school officials to all nine cases before students developed symptoms.
It turns out that what goes down the toilet has useful information when it comes to COVID-19. That’s because the virus can shed into an infected person’s stool days before symptoms develop. And that lag time presents an opportunity, says Oliver Griswold, chief marketing officer at Saint Joseph’s College.
“We’re using wastewater as an early warning system, basically. It is our first screen of whether we have COVID on campus,” he says.
And that early warning system apparently worked because wastewater testing was the first indicator that Saint Joseph’s had COVID-19 on campus. Going from a sewage sample to a single case is a process of elimination. It starts with campuswide testing, which Saint Joseph’s conducts twice a week.
“It gives us a very broad brush, up or down — ‘Yes, you have it. No, you don’t have it,’” Griswold says.
If the answer is yes, as it was recently, he says, the college next tests at the building level.
“So we tested all of the individual residence halls on campus, as well as some other buildings. And once we got a hit on that test, then we start individually testing every single person in that residence hall,” Griswold says.
And that’s how the cases were detected. All nine students were asymptomatic. Other schools have credited wastewater testing for halting large outbreaks, including the University of Arizona and Utah State University. It’s a strategy that’s also being deployed at the University of Maine.
“I never would have thought before this that that’s what I would be doing, but it turns out to be a really powerful tool,” says Rob Wheeler, an associate professor of microbiology at the University of Maine in Orono and a member of the University’s COVID-19 scientific advisory board.
Wheeler says the university just started wastewater sampling on the three campuses where the sewage stream doesn’t drain directly into the municipal system: the University of Maine in Fort Kent, Orono and Southern Maine. Wheeler says it bolsters the university’s testing strategy by capturing the whole population.
“Testing the whole population every week is something that is really logistically and financially quite demanding, and we’re not able to do that at this time. So, this provides kind of an adjunct to that,” he says.
The cities of Portland and Augusta are also performing wastewater testing to determine whether it’s an effective tool to detect cases of COVID-19 in municipalities.