Wastewater Monitoring Tool Tracks COVID-19 Trends, Public Health Threats

Researchers from Arizona State University and personnel from the city of Tempe, Arizona, have showcased the potential utility of a wastewater-based epidemiology (WBE) tool to provide health hazard detection and an early warning of public health threats, such as COVID-19, in a study published in The Lancet Microbe.

According to the press release, WBE is an emerging field of study that allows researchers to track chemicals and viruses in sewers and use that data to inform municipality-wide public health policies and interventions. The tool was developed in May 2018 to track opioid use, which allowed public health officials to pivot and use the existing population health monitoring infrastructure to detect SARS-CoV-2 in wastewater at the onset of the pandemic in April 2020.

The wastewater data is combined with other information, such as county and state data on vaccines and test results, to inform interventions.

“Wastewater science is a valuable tool for our city. The data helps us in determining where to set up clinics, intensify community outreach and adjust first responder operations,” said Wydale Holmes, interim director of the Tempe Strategic Management and Innovation Office, in the press release. “Our partnering with ASU and the trust from our community made this innovation possible."

Now, the collaboration has published data from the first large waves of the pandemic, from April 2020 through March 2021, in an open-access dashboard. Alongside the dashboard, ASU released their study examining how the WBE tool could be adapted to respond to emerging public health priorities.

Over the course of the study, wastewater samples were collected three days a week across 11 sites in the greater Tempe area. A total of 1,156 samples were collected. These showed two peaks in viral levels of COVID-19 one in June 2020 and another from December 2020 to January 2021.

During peak pandemic conditions at a Tempe hospital, the tool also revealed a maximum concentration of 37.6 million gene copies of SARS-CoV-2 per liter of wastewater. These concentrations correlated with the number of positive COVID-19 cases determined through clinical testing.

During the initial lockdown from May to June 2020, the dashboard also revealed elevated virus concentrations in the nearby town of Guadalupe, which could have led to a spike in cases and transmissions. However, prompt interventions spurred by these data, including community education and face-covering mandates, decreased these concentrations significantly.

“Data demonstrate that the monitoring of wastewater provides an early-warning capacity of over two weeks, thereby aiding in the confident prediction of future clinical caseloads, morbidity and mortality in our city and campus communities,” said ASU Professor Rolf Halden, PhD, in the press release. “The early-warning capacity of wastewater monitoring decreases once random clinical testing of individuals has been put in place, but the screening of individuals with conventional medical tools comes at a 60-fold higher price point than wastewater-based epidemiology, as our team demonstrated earlier this year. Thus, this latest study looking at all data collected over the course of the pandemic again highlights the power of wastewater monitoring as a nimble, practical and very economic health monitoring tool whose benefits extend to vulnerable populations of lesser economic means.”

Halden also noted that WBE may be particularly useful in situations where a substantial healthcare response has not yet been mounted, clinical testing sites and equipment are scarce, vaccination campaigns are delayed, testing fatigue has set in, or widespread use of at-home rapid tests obscures the true level of community infection.