SARS-CoV-2 Wastewater Measurements Normalized Using Biomarkers

As of November 2020, COVID-19 has led to more than 63 million cases and 1.47 million deaths with 270,481 of those deaths in the US. While COVID-19 commonly presents as a respiratory illness, symptomatic and asymptomatic individuals shed the COVID-causative agent (SARS-CoV-2) in their stool. This observation has motivated significant efforts to quantify SARS-CoV-2 in wastewater. The ultimate goal of these measurements is to offer an assessment of the disease prevalence within a community, which is an approach referred to as wastewater-based epidemiology. The quantification of SARS-CoV-2 in wastewater relies on concentrating and assessing the number of viral particles in wastewater using SARS-CoV-2 specific genes (nucleocapsid, N1 and N2). Recent work evaluated the performance of several concentration methods, including ultrafiltration, electronegative membranes, and polyethylene glycol (PEG) precipitation (1). The PEG method demonstrated high yield and consistent recovery. In the same study, for quantification, the SARS-CoV-2 N1 was measured at a slightly higher but significant value compared to N2. Work is ongoing to develop robust protocols for SARS-CoV-2 quantification. However, to fully realize the potential of wastewater-based epidemiology, additional methods must be developed to normalize the SARS-CoV-2 concentrations to population equivalence. It is well known that wastewater concentrations vary significantly with wet weather flow, thus a normalization technique must account for variations in wastewater strength. Wastewater concentrations under dry weather will also change with transient populations, and this is especially important for a college town or business community with commuter activity. Biomarkers can be used to determine the number of individuals contributing fecal matter to a sewershed. Ideally, biomarkers are specific to human waste, stable in wastewater, and consistently shed at known rates. This abstract reflects work to develop wastewater-based epidemiology as a tool to inform public health decisions by normalizing SARS-CoV-2 concentrations using four biomarkers. Weekly SARS-CoV-2 concentrations in influent wastewater were determined from two wastewater plants in Lawrence, KS. These concentrations have been normalized with four different biomarkers, and this SARS-CoV-2 data has been statistically correlated with COVID-19 case data. The overall purpose is to determine the most predictive metric for public health surveillance.