Tracking COVID-19 Using Wastewater—An Early Warning System
Topics: Public Health, Disease Outbreaks, Disease Transmission, Biochemistry, Biotechnology, Epidemiology, Immunology, Medicine
Typically flushed and forgotten, the warnings in our wastewater can tell us when our health and safety are at risk. Testing of wastewater reveals the presence of hazards—from toxins to viruses, including the SARS-CoV-2 virus—excreted from our bodies.
"Using wastewater surveillance as an early warning system is paying off in communities around the world," says MITRE biotechnologist Dr. Kunal Rambhia, who is leading the COVID-19 Healthcare Coalition activities related to wastewater surveillance.
Coalition members—including a wide range of public and private organizations—are working with universities and communities across the country to facilitate the development of wastewater surveillance as a tool for responding to the pandemic. Sharing information to help organizations prevent and contain COVID-19 cases is a key focus of the coalition.
In this case, that means connecting organizations with expertise in wastewater surveillance to universities and communities that want to develop programs.
Wastewater surveillance, also known as wastewater-based epidemiology (WBE), has been used for years around the world. But interest has grown significantly since the COVID-19 pandemic began. Universities, municipalities, and industry are creating new WBE systems to detect the virus and track it over time.
For example, the University of Arizona (UA) recently found evidence of the SARS-CoV-2 virus in sewage from one of its dormitories—before anyone exhibited symptoms. UA quickly tested everyone in the dorm and found two positive cases, both asymptomatic students.
They immediately put those students into a quarantine dorm to isolate them and started tracing their close contacts. Without a leading indicator—a warning—UA might not have discovered these cases until the virus had spread further.
Leading Indicators—Part of the Coronavirus Toolkit
The UA Water and Energy Sustainable Technology Center has many years of experience in conducting wastewater surveillance for the campus and the rest of Pima county. Before COVID-19, the center tested for 15 different human pathogenic viruses, as well as opioid use. The university's experts work in coordination with the local public health department and the Pima County Wastewater Treatment Plant.
As universities develop and evolve plans to bring students back to campus, wastewater surveillance is one of the many tools they can use to identify and control outbreaks on campus. Their toolkit also includes social distancing and wearing masks, as well as testing students and employees regularly (including, in many cases, when they arrive on campus), isolating those infected, and conducting contact tracing.
"Wastewater surveillance is an inexpensive, fast, scalable method to find leading indicators of disease," says Dr. Charles Gerba, microbiologist, and a professor of environmental science at UA's College of Agriculture and Life Sciences. He and other UA experts have been sharing their strategy and approach with other universities that are setting up WBE programs.
Building on Experience
Countries around the world have been using wastewater surveillance for years to determine where diseases are spreading. For example, the World Health Organization is successfully using this method to detect outbreaks of poliovirus. The agency then increases education and vaccination programs in targeted areas.
WBE has been used to detect hepatitis A, enteroviruses, rhinovirus, adenovirus, noroviruses, as well as different types of chemicals and opioids, within communities.
In the search for the SARS-CoV-2 virus, this leading indicator provides evidence of the virus approximately one week before patients become sick and are diagnosed and tested. An active infection will show up whether the person is symptomatic or asymptomatic; testing the wastewater allows widespread population testing without disruptions to day-to-day life.
Wastewater samples can potentially give local leaders an idea of how many cases are in a community and if the numbers are increasing or decreasing. Critical to the success of these efforts is a plan for what to do when the wastewater tests positive for SARS-CoV-2.
WBE does not replace individual diagnostic testing, rather it is part of a multifaceted system to contain the virus. It helps public health officials and other decision makers identify who needs to be tested, isolated, and helped through treatment and contact tracing.
Down to the Genomics
To conduct wastewater surveillance, an individual or a device captures a sample from a wastewater plant or an individual building's sewer line. That liquid or solid sample is processed by a lab and the genetic signature of the virus, found in its ribonucleic acid (RNA), is extracted and analyzed.
"The test they run on the RNA is actually very similar to the assay that's brought into diagnostic testing for clinical purposes. It's a PCR-based [polymerase chain reaction] assay," Rambhia says.
Yale University monitors its own wastewater as well as that of New Haven and several cities in Connecticut. Its scientists work with Connecticut Public Health departments to provide them with data depicting the state of the virus. (See their dashboard)
"We've been sampling every day since March 19. Particularly early in the pandemic, this has been a good way to predict when a surge of cases will hit the hospitals," says Dr. Jordan Peccia, Yale's Thomas E. Golden, Jr., Professor of Chemical & Environment Engineering.
"We consider wastewater surveillance as one of the tools our leaders use to make decisions—the more data, the better."
A Fast-Moving Target: Characterizing the Virus
The coalition has worked with universities across the country to identify and share best practices for developing an end-to-end process for implementing WBE systems. Members are also exploring ways to improve these systems and support an effort to share data across systems, which would provide a bigger picture of the virus's presence nationwide.
Because this virus is new and moving so quickly, scientists and microbiologists are still learning about it and how it spreads. Questions include:
How fast does it break down in wastewater/sewage?
How often do we need to test for it?
How can we correlate viral concentrations in wastewater with recorded number of infections?
Each method has complexities in how samples are collected and processed and how data is analyzed. While many of the current efforts are happening independently, there's a significant need to facilitate the interpretation of data across municipalities, particularly when organizations use different methods to generate data.
Coalition members are pursuing ways to create common data standards for characterizing the virus in WBE, which will allow organizations to compare data across boundaries and time.
Members also continue spreading the word about how to interpret the warnings within the surprisingly informative world of wastewater.
The presence of SARS-CoV-2 RNA within wastewater offers an opportunity to:
1. Detect trends in disease burden within a population prior to changes in cases and deaths
2. Identify the presence of the virus in an otherwise uninfected population (e.g., one or two students within a dormitory)
3. Monitor the genetic evolution of the virus
4. Estimate the prevalence of disease within a population at a given point in time.
—by Beverly Wood
News Story: "University of Arizona's wastewater testing halts potential surge in COVID-19 cases at dorm"
UIDP Webinar: "Using Collaboration to Accelerate Solutions in COVID-19 Response"
ORAU Podcast: "Wastewater Surveillance and COVID-19"
ORAU Webinar: "Surveillance for SARS-CoV-2 Using Wastewater—A Leading Edge Indicator"
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