Why the New National Wastewater Surveillance System Matters
Testing sewage for RNA from SARS-CoV-2 has become part of a comprehensive surveillance strategy for communities responding to COVID-19 across the U.S. Having recognized that this wastewater testing offers significant advantages, the Centers for Disease Control and Prevention (CDC) and the Department of Health and Human Services (HHS) began developing a new National Wastewater Surveillance System (NWSS).
The CDC and HHS first announced the new tool in August, saying that it will include a portal for state, tribal, local, and territorial health departments to share wastewater testing data, helping public health officials better understand community spread.
"Sewage testing has been successfully used as a method for early detection of other diseases, such as polio," the CDC points out online. "Depending on the frequency of testing, sewage surveillance can be a leading indicator of changes in COVID-19 burden in a community." The agency also notes that wastewater surveillance can capture data on both symptomatic and asymptomatic infections.
Public health officials have seen how wastewater-based epidemiology can help prevent outbreaks. In August, the University of Arizona's sophisticated surveillance system caught asymptomatic cases early. Now, with data from Johns Hopkins University (compiled by CNN) showing case increases in most states, time is of the essence. Labs have an opportunity to help by contributing their expertise to national efforts and providing timely testing services.
Wastewater Testing to Provide Advance Notice
Searching for SARS-CoV-2, the virus that causes COVID-19, in sewage might have seemed novel when the pandemic began, but this approach has actually been around for many years. Microbiologist Yolanda Brooks, assistant professor of biology at Saint Joseph's College, said in an interview for Currents that sewage testing has been used to detect diseases, as well as opioid crises and hepatitis A outbreaks.
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Recent research underscores the difference that wastewater testing can make for COVID-19 surveillance, especially in areas experiencing delayed diagnostic test reporting. A Yale University study published in Nature Biotechnology on September 18 measured SARS-CoV-2 RNA concentrations in primary sewage sludge in the New Haven metro area throughout a 10-week period last spring. Those results led hospitalizations by one to four days and positive test results by approximately one week (by reporting date).
"Our data show the utility of viral RNA monitoring in municipal wastewater for SARS-CoV-2 infection surveillance at a population-wide level," the scientists write. "In communities facing a delay between specimen collection and the reporting of test results, immediate wastewater results can provide considerable advance notice of infection dynamics."
A Key Component of the Public Health Toolkit
COVID-19 sewage surveillance isn't meant to be a replacement for clinical testing. Instead, it's a complement to diagnostic testing that should be part of a public health toolbox, according to a CDC webinar presented to the Council of State and Territorial Epidemiologists in July. CDC microbiologist Amy Kirby noted during the presentation that some reports show stool shedding will precede respiratory shedding.
"That early shedding plus the short residence time in the sewage network plus a rapid test method mean that we may be able to detect changes in incidence in a few days versus the clinical indicators that can lag by up to two weeks," she said.
The CDC, HHS, the Environmental Protection Agency (EPA), and the other federal agencies on the National Sewage Surveillance Interagency Leadership Committee view sewage surveillance as a data source that can assist with local and state decision-making, particularly around whether to reopen or re-close.
Expanded National Initiatives
CNBC reported in late September that HHS is expanding national efforts, posting a notice "seeking bids from contractors that can carry out a plan to test up to 30% of the country's wastewater to act as an 'early warning system' for coronavirus outbreaks." Around the same time, a group of lawmakers urged the CDC to invest federal funding in wastewater-based epidemiology, highlighting its cost-effectiveness and its ability to provide data on people in the community who have not been clinically tested.
Currently, the EPA is working on the Ohio Coronavirus Wastewater Monitoring Network. This collaborative initiative, which includes the Ohio Department of Health, the Ohio EPA, the Ohio Water Resources Center, and several participating universities, establishes a network across the state to study samples. According to a U.S. EPA statement from early October, the CDC is using efforts like this to develop recommended approaches for the NWSS. The EPA's project in Ohio expands sampling capacity, facilitates interlaboratory comparisons, and standardizes data-reporting approaches, the agency said.
How Your Lab Can Get Involved
"Using wastewater surveillance for public health action requires a multidisciplinary approach," says the CDC's NWSS website. Lab scientists should serve as local partners for testing, the agency explains. Public health, environmental, academic, and private labs all have a chance to get involved.
Your insights on environmental surveillance may be essential to building national capacity. Labs can share expertise on how to select a wastewater testing method that will be consistent, scalable, and enable data comparison across different locations.
And if wastewater testing for SARS-CoV-2 is within your ability, consider offering the service. Communities need effective public health tools in the ongoing fight against COVID-19.
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