By Will Atwater
While coronavirus cases have declined, the pandemic is not over and requires constant monitoring to provide advanced notice of new variants if they emerge.
In 2020, the Centers for Disease Control and Prevention launched the National Wastewater Surveillance System (NWSS), an early detection tool, which alerts communities of SARS-CoV-2, the virus that causes COVID. The wastewater monitoring process is noninvasive for households, as researchers collect samples from local wastewater plants and provide analysis without having to interact with individual residents.
Last month, Amy Kirby, who leads the CDC’s surveillance system, announced at a press conference that “data are available for the first time on CDC’s COVID Data Tracker,” which is available online.
She explained that between 40 and 80 percent of people infected with COVID shed viral RNA in their feces, which makes wastewater testing an important tool for monitoring the spread of infection.
“What started as a grassroots effort by academic researchers and wastewater utilities has quickly become a nationwide surveillance system with more than 34,000 samples collected representing 53 million Americans,” Kirby said.
How the system works
Here in North Carolina, a multi-step process involves wastewater samples being collected and analyzed for the presence of the virus that causes COVID-19. After that, data is passed on to the CDC and analyzed for trends before, ultimately, landing in the North Carolina Department of Health and Human Services COVID dashboard.
Currently, there are 25 municipalities statewide providing wastewater samples, with 12 more expected to join soon.
The University of North Carolina at Chapel Hill Institute of Marine Sciences researcher Rachel Noble and her team participate in this program by providing analysis of local wastewater samples weekly at her Morehead City lab before shipping them to the CDC.
Noble says that while it may take a few days from the time the wastewater samples are collected before the information is available on the state health department dashboard, her lab and collaborators work hard to make the process as efficient as possible.
“These data are uniquely powerful because they capture the presence of infections from people with and without symptoms,” Kirby said. “And they’re not affected by access to health care or availability of clinical testing.”
Challenges in rural communities
There are some limitations with the early-detection program.
There are more than 400 wastewater testing sites across the country but around 20 percent of households rely on septic systems to collect wastewater and are not part of the data collected, Kirby noted. The majority are in rural communities, outside the reach of municipal sewersheds.
In North Carolina, it’s estimated that 40 to 50 percent of households are connected to septic systems, which hampers researchers’ ability to analyze data from rural communities.
To address this problem, Virginia Guidry, head of the Occupational and Environmental Epidemiology Branch at the DHHS, works with the local academic community to find ways to pull more rural communities into the program.
“We partner with UNC researchers on this project. And that’s a clear question we’ve talked to them about … what ideas and kind of innovative approaches we might be able to use to cover the rural areas.”
However, there are some limited tools for gathering wastewater data from rural residents.
“People who live in homes that are on septic systems don’t necessarily just stay put and only use their home for sanitation, they go other places,” Noble said. “We do capture a lot of individuals that are doing their business around town by having the municipalities on our wastewater surveillance program.”
At the national level, Kirby said the CDC is working to provide additional resources to states to increase data collection capacity. And that she “expects those resources to be available through COVID data tracker in the next few months.”
Looking back to move forward
Using wastewater surveillance systems to identify infectious pathogens in communities was used long before the coronavirus pandemic arrived.
An earlier form of wastewater monitoring was used in the U.S. to trace the spread of the poliovirus, and later to track the poliovirus vaccine’s effectiveness.
Wastewater surveillance continues to be used in countries that are still battling polio, such as Pakistan and Afghanistan, in an effort to eradicate the disease, according to an article published in The Conversation.
Even as the CDC and states work to clear hurdles that are preventing more rural communities from participating in COVID-19 early detection, officials are already looking to the future.
During last month’s CDC press conference, Kirby discussed future goals for wastewater surveillance that go beyond COVID-19 monitoring to include other pathogens that could pose a threat to public health, including influenza, norovirus and foodborne infections such as E. coli and salmonella. She anticipates the NWSS expansion to begin by the end of this year.
‘A cause for concern’
While expanding wastewater surveillance is a welcomed public health advancement, some communities may have a cause for concern going forward. Historically, many in African American and Native American communities have been skeptical of government-initiated projects, with good reason as several have led to worse outcomes for them.
In an effort to help facilitate wastewater surveillance across the U.S., the Rockefeller Foundation recently developed the Wastewater Action Group with a goal to expand wastewater testing to underserved populations.
Recently, in an online interview, two Action Group members discussed their work in African American and Native American communities and shared some of the concerns they have heard from these communities related to wastewater surveillance.
Otakuye Conroy-Ben, assistant professor at the School of Sustainable Engineering and the Built Environment at Arizona State University, works with tribal communities in the western United States in many areas, including wastewater surveillance.
She said while most tribes welcome the information provided by wastewater surveillance, there are certain procedures that researchers and public health officials need to abide by when working in tribal communities.
“In general, tribes have … their own data sovereignty policies for data sharing, data ownership,” Conroy-Ben said. “And if any data is collected within their reservation boundary … that information is owned by the tribe.”
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Na’Taki Osborne Jelks, assistant professor of environmental health at Spelman College, works with African American residents in Atlanta on outreach projects that include wastewater surveillance monitoring.
While residents appreciate the benefits of participating in a COVID-19 early-detection system as they emerge from isolation to reclaim social activities such as gathering for Sunday worship, Jelks said there is some skepticism because of past experiences.
“When you talk about communities of color, we talk about low-income communities. Many communities feel overstudied yet underserved at the same time.”
As the NWSS becomes more established and more capable of monitoring for a host of pathogens, experts are debating what safeguards would need to be in place to protect specific communities from being unfairly targeted. For instance, could monitoring for illicit drug use be on the horizon?
Such questions highlight the need to develop equitable policies that will guide the use of wastewater surveillance as it becomes more established.