A dirty job: NC researchers use wastewater to detect COVID-19 and understand it
Next year, the Centers for Disease Control and Prevention will analyze what North Carolinians and residents of a handful of other states flush down their toilets in an effort to detect the coronavirus.
With the help of government funding, North Carolina researchers launched a wastewater surveillance system this year to serve as a supplemental method of helping public officials detect and understand COVID-19 in their communities.
Those researchers are optimistic that the system will be equipped to detect other diseases in the future. North Carolina will be one of just eight states in January that funnels their wastewater data to the federal government to track the coronavirus.
“We have our eye on the prize of improving the health overall of people in North Carolina,” said microbiologist Rachel Noble of the UNC Institute of Marine Sciences, who is leading the effort in the state. “This is a long-term investment in the health of people in North Carolina.”
Because coronavirus vaccinations are already starting to be administered, researchers like Noble hope the data will show in the coming months that concentrations of the coronavirus in wastewater are decreasing, rather than rising, as it has in recent months.
“We’re trying to turn it into a good thing,” Noble said. “Originally we were tracking a bad thing, but now we’re hoping that things will turn around.”
Laying the groundwork
Wastewater surveillance isn’t new. It’s already proven successful in identifying polio outbreaks and monitoring opioid use. Noble’s team in particular has been tracking pathogens — like norovirus, hepatitis A and gastrointestinal viruses — in wastewater since the 1990s.
Weeks before the coronavirus was identified in the United States, Noble’s lab manager, Denene Blackwood, was thinking about what they could do to get ahead of the disease.
“We already had everything in stock before anyone else,” including PPE like masks and gowns, Noble said. “(Blackwood) was gearing up because she was interested in the potential for doing this work.”
By the beginning of March, when North Carolina announced its first coronavirus case, Noble and her team were already laying the groundwork to begin identifying concentrations of COVID-19 in wastewater.
Between the end of March and early April, her team began collecting sewage samples, allowing them to detect COVID-19 shed in fecal matter.
State lawmakers then allocated some $29 million of federal coronavirus relief funding to the North Carolina Policy Collaboratory supporting research of treatment, testing and prevention of COVID-19. Nearly $2 million of that went to wastewater surveillance.
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Researchers at UNC-Charlotte, UNC-Chapel Hill, N.C. State and UNC-Wilmington are tracking the virus at about 20 wastewater treatment plants of various sizes across the state.
For now, wastewater data serves as an aggregate measure of larger trends, namely whether cases are rising or falling in any given town or city.
“Now we’re getting a big picture perspective of what’s really going on in the towns,” Noble said.
An early detector
This method of detecting the virus can identify the presence of the coronavirus before someone even knows they have it.
And it solves some of the problems that come with clinical testing, Noble said, by identifying the coronavirus among people who are asymptomatic and thus, may not have gotten tested otherwise.
By identifying asymptomatic cases, researchers may detect a rise in cases before testing confirms them.
Wastewater surveillance can also capture cases of the virus in people who may choose to forgo testing or lack access to getting a test.
“The wastewater work is different, because anyone who lives in a town or city in North Carolina, if we are working on that municipality’s wastewater, if they are ill and they flush the toilet, they are part of the signal that we measure,” Noble said.
Noble emphasized, however, that wastewater surveillance data is not meant to replace clinical testing, only supplement it.
But even the aggregate data could be used to inform public health officials on what policies — like mask mandates and school closures — they could implement based on case trends.
“The CDC is counting on us... to be generating data that is useful not only to the state of North Carolina but is also useful to them to understand how things are working,” Noble said.
Some universities are also using surveillance to track the coronavirus on a smaller scale, including in residence halls on campus. But the end goal of that surveillance differs slightly from the goals of Noble and other researchers tracking the virus in more populated areas.
Campuses may use wastewater surveillance to decide whether to keep the school open, or determine how well the virus is being managed on campus, Noble said.
At some point in the near future, researchers hope they will be able to estimate how many people have the virus using wastewater data.
“We’re still a little far away from being able to say that with much confidence right now,” said Angela Harris, a professor at N.C. State who is part of the team working with Noble. “Often right now, it’s being used for trend analysis. How much we see in the wastewater, how does it compare to what we saw back in July, when there was a peak of cases?”
This story was originally published December 28, 2020 at 6:15 AM with the headline "A dirty job: NC researchers use wastewater to detect COVID-19 and understand it."
