Nationwide trends in COVID-19 cases and SARS-CoV-2 wastewater concentrations in the United States

Abstract

AbstractWastewater-based epidemiology has emerged as a promising technology for population-level surveillance of COVID-19 disease. The SARS-CoV-2 virus is shed in the stool of infected individuals and aggregated in public sewers, where it can be quantified to provide information on population-level disease incidence that is unbiased by access to clinical testing. In this study, we present results from the largest nationwide wastewater monitoring system in the United States reported to date. We profile 55 locations with at least six months of sampling and highlight their wastewater data from April 2020 through May 2021. These locations represent over 12 million individuals across 19 states. Samples were collected approximately weekly by wastewater treatment utilities as part of a regular wastewater surveillance service and analyzed for SARS-CoV-2 concentrations using reverse transcription quantitative polymerase chain reaction (RT-qPCR). Concentrations of SARS-CoV-2 (copies/mL) were normalized to pepper mild mottle virus (PMMoV), a stable and persistent indicator of feces concentrations in wastewater. Here, we show that wastewater data reflects temporal and geographic trends in clinical COVID-19 cases, demonstrating that wastewater surveillance is a feasible approach for nationwide population-level monitoring of COVID-19 disease. We also provide key lessons learned from our broad-scale implementation of wastewater-based epidemiology, which can be used to inform wastewater-based epidemiology approaches for future emerging diseases. With an evolving epidemic and effective vaccines against SARS-CoV-2, wastewater-based epidemiology can serve as an important passive surveillance approach to detect changing dynamics or resurgences of the virus.HighlightsWe present results from a nationwide wastewater monitoring network in the United States, which represents one of the broadest temporal and geographic wastewater-based epidemiology datasets to-date.Wastewater concentrations measured within individual locations reflect temporal trends in reported COVID-19 cases in the associated communities.Wastewater concentrations also reflect geographic patterns in reported COVID-19 cases across states throughout the pandemic.Normalizing wastewater concentrations to a fecal marker virus improves the correlation between wastewater data and clinical cases across locations but not necessarily over time within individual locations.Implementing a nationwide wastewater monitoring system for SARS-CoV-2 is feasible, practical, and sustainable.