Back in July, scientists detected noninfective fragments of coronavirus RNA in raw sewage at Yosemite National Park, revealing, unfortunately, that visitors had been carrying—and depositing—the virus since the park reopened the previous month.
Though it may seem a bit unsavory, studying human waste can tell us a lot about COVID-19 and give governments a leg up on containing the spread of the virus. Researchers can predict if the coronavirus might attack a community by checking sewers for viral fragments in the community’s poop; preliminary studies from earlier this year, conducted by the Centers for Disease Control and Prevention (CDC), academia, and other research organizations, indicated that communities might see an increase of the coronavirus in wastewater two to four days before a spike in hospitalizations. Using this wastewater-based epidemiology (WBE) approach, the public health community is banding together to identify and treat health threats in a non-invasive way.
The Department of Homeland Security (DHS) Science and Technology Directorate (S&T) recently joined a multiagency WBE initiative that will not only gather virus data from sewer systems but standardize the science. The coalition is led by the CDC National Wastewater Surveillance System, whose goal is to turn sewers into health monitors. CDC is also collaborating with the Department of Health and Human Services and agencies like the U.S. Environmental Protection Agency, Food and Drug Administration, and DHS, to accelerate the WBE research. The goal is to better understand the spread of the virus in communities to contain and defeat it.
Collectively, WBE isn’t focusing on an individual’s health. Here, the testing is focused on the health of whole communities to get ahead of, and flatten, the curve during the pandemic. Instead of testing everyone, scientists can use this method to screen for areas in which populations should be offered more testing and encourage these populations to strictly follow emergency public health guidelines.
For its part, S&T is working with the National Institute of Standards and Technology (NIST) and the University of Louisville School of Medicine to develop guidelines to standardize WBE testing methods nationwide. Because there are currently many ways to test wastewater, data gathered from across the U.S. could be difficult to compare; using the new standards, the data can be more readily shared and compared across cities, states and regions to inform more effective healthcare decisions. For example, knowing through reliable WBE data where outbreaks are occurring and how severe they are can inform critical decisions on prioritizing personal protective equipment, immunizations, and customizing countermeasures.
“The proposed standards will help guide an appropriate sampling and testing strategy designed around the existing infrastructure,” said Philip Mattson, the DHS standards executive at S&T. “We can't get this job done alone. We are partnering to accelerate these solutions so that other communities across the U.S. can benefit as fast as possible and make more informed decisions using science-based guidance.”
In May 2020, S&T started working with the University of Louisville on the standards project, focusing on sampling and testing methods tied to defined epidemiological frameworks. These standards will not only help with this pandemic but also with future public health threats and ongoing population health risks.
The Louisville researchers use 24-hour timed autosamplers installed in manholes and send them to multiple labs for analysis to see how much coronavirus RNA is in the samples. Then the researchers compare the data with the findings of representative COVID-19 random sampled testing of residents done every eight weeks across the city. A single sample could provide insight into the infection prevalence of a whole community, making this testing very cost effective.
The researchers are also monitoring other catchment areas, including the northern Kentucky’s Sanitation District No. 1, the state prisons, nursing homes and a small rural town. The purpose is to learn at what geographic scale sampling should occur—at a building level, campus level, neighborhood level or at an entire city level—and how everything should work together. That has not been established.
“If you say, ‘I'm sampling a dorm,’ then the next questions are ‘What sampling method is most appropriate? Which laboratory analysis and epidemiologic model might be most appropriate?’” said Dr. Ted Smith, University of Louisville professor of environmental medicine. “It is really important as a country to be clear about these different scales because there are different implications for public health consequences and countermeasures.”
But developing standards takes time. “Standard guidance documents and physical standards, such as reference materials, are critical for data comparability and help ensure that high quality results are provided to decision makers,” said Nancy Lin, a NIST biomedical engineer who co-leads the WBE standards development.
The good news is that these standards are not only for COVID-19. They are expected to be applicable for many kinds of environmental health risks, like detecting other pathogens or potentially exposures to dangerous chemicals. Additionally, health status biomarkers, like the stress hormone cortisol, for a population in a facility, neighborhood or entire community may one day soon be gleaned on a near-real-time basis. These biomarkers could provide insights into trends in prescription and illicit drug use, and risk factors, such as smoking, for many chronic diseases.
Using WBE to passively monitor biological and chemical data can inform governments, health insurers and health providers how to better service communities. For example, if heart disease patients also live in highly polluted areas where high levels of breakdown products from air pollution can be found in urine, physicians may consider that additional location-based risk data when treating those patients. Health insurers can decide where to offer their products such as managed Medicaid. City planners could develop more localized health risk mitigation like planting air pollution vegetation barriers (trees, shrubs, etc.). With WBE, we can also have an early warning of toxic chemical spills so emergency managers could track the duration and extent of such disasters.
“New kinds of commercial laboratory and data analytics companies can develop a panel of pathogens, toxins, and health status biomarkers that we regularly check to assess a population, and we could potentially identify a problem much earlier and then make a much bigger difference in its trajectory,” Smith explained. “This would improve our health and resilience as a country and therefore be more competitive and more productive.”
Moreover, with standardized WBE research becoming integrated into the infrastructure, more jobs could be created as more technologies used for monitoring the sewer systems are built by private companies, who also participate in gathering and delivering samples to the labs.
“We want to deliver something that is useful, that can go to the field and help people make appropriate decisions with the standardized guidelines we provide,” Mattson said. “Our role is just one piece that fits into this overarching multiagency National Wastewater Surveillance System. We are glad to be lending our expertise to this multi-agency effort and look forward to having these standards in place to keep our communities safe.”