As the pandemic progresses, researchers have been using all kinds of metrics to track the virus as it spreads through communities.
Some have been using a surprising, but at times effective, method – analyzing wastewater.
"Wastewater monitoring is happening all over the world," said Alexandria Boehm, professor of civil and environmental engineering at Stanford University on KCBS Radio's "Ask an Expert" with Holly Quan and Dan Mitchinson on Friday.
Using wastewater to track infections in communities is not a new method, said Boehm, in the past it has been used in Israel to track polio outbreaks. But it is a new method for tracking respiratory illness.
At the very beginning of the pandemic environmental engineers who work on wastewater, public health, and pathogens started looking to see if the COVID-19 virus could be detected in wastewater. "And we were really surprised we could detect it," she said.
What these environmental engineers look for is the viral genome, the RNA of the virus. "It's excreted by people, basically dead," said Boehm, in people’s poop. "Into the toilet and ends up in the wastewater."
This form of the virus is not infectious, and can't be transmitted via feces, she said.
The water is treated at a waste treatment plant, but researchers can collect it beforehand and test for virus concentrations in the water. Those concentrations can paint a pretty clear picture of how much of the virus is present in that community.
And the results come very quickly, in less than 24 hours, and don't need clinical testing results, she said.
"Looking at the wastewater actually gives us a glimpse into the true presence of infections that doesn't rely on human behavior and people going out to get tested and getting those testing results which can sometimes take a few days," said Boehm.
While testing is pretty open and widely available in the Bay Area, the same can't be said for other communities elsewhere, so this method helps fill that gap of information, she said.
Testing at airports, like recent work being done at SFO, can help provide context for how prevalent the virus is among international travelers, and provide clues as to what new variants are emerging.
"We've already been looking for the omicron variant in wastewater in the Bay Area," she said. "People have also been looking at it in other locations, and we also have been looking at delta in the wastewater."
It’s also relatively inexpensive, even cheaper, than conducting individual clinical testing. And unlike clinical testing, people don’t have to be tested voluntarily.
"People don't have to opt in to excreting into the toilet, we all do it every day, it’s part of being human," said Boehm.
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