by Kevin Schofield

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This weekend’s read is a new report from the National Academy of Sciences looking at using wastewater to conduct surveillance for diseases.

The National Academy of Sciences, along with its sister organizations the National Academies of Engineering and Medicine, are federally funded nongovernmental bodies made up of the leading researchers in their domains. The government established the National Academies so Congress (and occasionally the executive branch) can ask them to investigate a particular question or issue and report back with their findings. The mere existence of the National Academies makes me proud of our country and reminds us what we can do at our best: We can put in place a permanent facility to harness our best minds to solve problems independent of politics. The National Academy of Sciences was founded in 1863, approved by President Lincoln in the midst of the Civil War.

In the case of this study, the Centers for Disease Control and Prevention (CDC) contracted with the National Academy of Sciences to look at issues surrounding wastewater analysis for disease detection. During the COVID-19 pandemic, the government spun up the National Wastewater Surveillance System (NWSS) to sample wastewater from local sewer systems and test it for the presence of the virus. This kind of analysis is not new: The government did similar wastewater analysis in the 1940s looking for polio, an effort that extended into the 1970s. This time, the NWSS got off to a slow start, but as of last October, there were over 1,205 sites spread across 42 states and covering 133 million individuals living in our nation. 

The NWSS turned out to be effective at detecting — and, in many cases, predicting in advance — COVID-19 outbreaks. The fecal matter of infected people (i.e., their poop) contains the virus, even for people who aren’t showing symptoms. While community-level wastewater detection can’t identify individuals who are infected, the level of virus in wastewater samples, which combine the outflow from many individual buildings, can give a very accurate reading of the overall level of infection in a community. During the pandemic, local health departments that had access to NWSS data could use it, in combination with other public health data, to make better-informed recommendations to the community. According to the CDC, 11 counties in Washington State report data to the NWSS.

The NWSS has also been useful for detecting the spread of emerging COVID-19 variants. It was also used last year during the mpox and polio outbreaks to identify local communities the virus had infected — and which communities it seemed to miss.

Not surprisingly, the National Academy of Sciences argues in its report for a permanently funded national wastewater surveillance network through maintaining and strengthening the current NWSS. Doing so would require more and better testing facilities and regular ongoing testing. That, in turn, requires deciding what specifically to test for, and the report suggests three criteria: the public health significance of the threat, the feasibility of testing for it, and the usefulness of the data to inform action by public health departments. 

But a permanent NWSS could also take and archive wastewater samples on a regular schedule so scientists could test after the fact for the presence of diseases. Consider, for example, the original spread of COVID-19: There are hypotheses that it was spreading in the United States as early as November 2019, but one of the reasons it took so long to acknowledge the pandemic threat is that we had no good data on how widespread it had already become. While on one hand the notion of some government warehouse containing years of poop-water samples from across the United States might put you off your lunch, it could be a very valuable resource in the early days of the next pandemic.

A nationwide wastewater surveillance network could also focus on “sentinel sites,” which are largely self-contained facilities that draw people from a wide geographic area and are considered high-risk for the spread of infectious diseases, including airports, convention centers, universities, and theme parks. Sentinel sites could also include high-risk facilities such as prisons and larger long-term care facilities, where an outbreak is particularly problematic.

The report raises several issues that need to be addressed as well. One is equity: While there are over 1,250 surveillance sites in the current NWSS, they are not evenly distributed — they are overly concentrated in metropolitan areas and are sparse in southern and mountain states. Also, it’s unclear how to cover “unsewered” communities, in rural and poorer communities, where there aren’t central locations to take samples that represent a larger population.

Privacy is another issue: People need and deserve assurances that the data collected won’t be used for other purposes that might harm individuals. At the moment, the tests look for the presence of “biomarkers,” fragments of the DNA or RNA of a pathogen. But if in the future it becomes possible to identify infected human cells in wastewater, could DNA analysis be used to identify specific individuals who are infected? It isn’t even close to possible today, but now is the right time to ensure that scientific advances don’t lead to personal intrusions. The report recommends clear public communications on privacy issues and that an ethics advisory committee be created to discuss and make recommendations on the privacy issues related to wastewater surveillance.

Another important issue is ensuring that a full, permanent NWSS has the right level of coordination with state and local public health organizations — and with local sewer utilities where the sampling will need to take place. During the COVID-19 pandemic, the CDC was often criticized for poor coordination with state and local agencies, and more broadly for the fact that it had not developed a network of connections and relationships that would allow for rapid response, coordination, and effective communication to the public during a pandemic event; solving those problems would be even more important in creating a permanent NWSS.

Finally, it points out that academia and the scientific community will need to be involved, both to drive innovation in testing and analysis, and also to ensure that there is a properly trained workforce to staff the surveillance network.

The preface of the report ends with a comment, essentially “we’ve been here before and we screwed it up”:

The history of public health funding in the United States, and specifically for disease surveillance, is one of emergency response to disease epidemics followed by a precipitous decline once the immediate threat has passed—only to be rebuilt with the next infectious disease event. The impacts of the COVID-19 pandemic, which touched everyone, has, hopefully, forever changed this approach. Having built on the innovation and expertise of all those who brought the wastewater surveillance system to the point where a true national system is within reach, it is a pivotal moment to ensure that it achieves its promise.

Wastewater-based Disease Surveillance for Public Health Action

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📸 Featured image by Aleksandar Malivuk/Shutterstock.com.

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