SARS-CoV-2 accumulation in sewer biofilms and Outbreak Surveillance through Wastewater-Based Epidemiology in the State of New Jersey

Wastewater based epidemiology grew in popularity during the COVID-19 pandemic showing particular utility where individual testing was infeasible due to the cost, lack of testing supplies, non-compliance, and other challenges. Here, a monitoring study was performed across four wastewater collection systems with varying size and design (e.g., two combined sewer systems compared to two separate sanitary sewer systems). Generally, correlations between the previous week’s testing results correlated best with N1 gene copies observed in the sewage. To understand the potential for attenuation and accumulation of SARS-CoV-2 gene copies in sewer biofilms, swabs were collected from select pipes and an annular biofilm reactor was used to simulate the loading and shear in sewer pipes. SARS-CoV-2 was above detection in the simulated sewer biofilm when cases were too low to quantify in the wastewater and accumulated over the second wave of cases in the study region. Results presented here can provide insight into interpretation of wastewater-based epidemiology data.