Fine-Scale Temporal Dynamics of SARS-CoV-2 RNA Abundance in Wastewater during A COVID-19 Lockdown

Wastewater is a pooled sampling instrument that may provide rapid and even early disease signals in the surveillance of COVID-19 disease at the community level, yet the fine-scale temporal dynamics of SARSCoV-2 RNA in wastewater remains poorly understood. This study tracked the daily dynamics of SARS-CoV2 RNA in the wastewater from two wastewater treatment plants (WWTPs) in Honolulu during a rapidly expanding COVID-19 outbreak and a responding four-week lockdown that resulted in a rapid decrease of daily clinical COVID-19 new cases. The wastewater SARS-CoV-2 RNA concentration from both WWTPs, as measured by three quantification assays (N1, N2, and E), exhibited both significant inter-day fluctuations (10 1.2-10 5.1 gene copies or GC/L in wastewater liquid fractions, or 10 1.4-10 6.2 GC/g in solid fractions) and an overall downward trend over the lockdown period. Strong and significant correlation was observed in measured SARS-CoV-2 RNA concentrations between the solid and liquid wastewater fractions, with the solid fraction containing majority (82.5%-92.5%) of the SARS-CoV-2 RNA mass and the solid-liquid SARSCoV-2 RNA concentration ratios ranging from 10 3.6 to 10 4.3 mL/g. The measured wastewater SARS-CoV-2 RNA concentration was normalized by three endogenous fecal RNA viruses (F + RNA coliphages Group II and III, and pepper mild mottle virus) to account for variations that may occur during the multi-step wastewater processing and molecular quantification, and the normalized abundance also exhibited similar daily fluctuations and overall downward trend over the sampling period. (c) 2021 Elsevier Ltd. All rights reserved.

Automated summary

This study tracked the daily dynamics of SARS-CoV-2 RNA in wastewater from two wastewater treatment plants in Honolulu, revealing fluctuations and a downward trend in the concentration of SARS-CoV-2 RNA. Strong correlation was observed between the solid and liquid fractions of wastewater in terms of SARS-CoV-2 RNA concentration.