Tests performed on sewage from homes in part of Northern Virginia indicate more COVID-19 cases than what other testing methods have found.
Stafford County is having its wastewater analyzed to detect the virus.
“What they can determine is the genetic fragments of the virus still in the wastewater,” public works director Jason Towery explained.
The county’s water treatment plants package samples of wastewater every day and send them to be analyzed by a Boston lab called Biobot.
Stafford County stepped forward early in the coronavirus pandemic and has already received striking results.
Northern Virginia news, events and updates
Early testing shows about 3 to 6% of the community had likely contracted COVID-19.
In August, that figure climbed to between 6 and 9%, with some samples testing as high as 18%.
“The wastewater is showing there is likely larger spread than what some of the other traditional methods of testing are showing right now,” Towery said.
Analyzing wastewater is especially valuable because the virus will show up in waste immediately once someone contracts the coronavirus, whether or not they have symptoms or know they're positive.
County officials say they hope sewage testing can serve as an early warning system for any outbreaks.
Biobot Founder Mariana Matus said she envisions this kind of testing becoming routine at water treatment plants nationwide.
“With only a few thousand tests, you can get data that represents everyone,” she said.
It may even help us get ahead of any future pandemics, Matus added.
Stafford County and Biobot are still gathering data and not taking any action based on early results. What gets flushed will be studied at least through the end of this year.
Alexandria, Purcellville and Richmond also are taking part in sewage studies.
The Centers for Disease Control and Prevention and other federal agencies launched the National Wastewater Surveillance System in mid-August. Labs, state governments and local governments can submit test results to the database.
Tests can detect RNA from SARS-CoV-2, the virus that causes COVID-19, the CDC explains. While the virus can be found in the feces of people with COVID-19, there’s no information that indicates that anyone has contracted the virus from contact with treated or untreated wastewater, according to the CDC.
Sewage testing has previously been used as a method for early detection of diseases including polio.