Decay of SARS-CoV-2 and surrogate murine hepatitis virus RNA in untreated wastewater to inform application in wastewater-based epidemiology

Abstract

Wastewater-based epidemiology (WBE) demonstrates potential for COVID-19 community monitoring; however, data on the stability of SARS-CoV-2 RNA in wastewater are needed to interpret WBE results. The decay of RNA from SARS-CoV-2 and a potential surrogate, murine hepatitis virus (MHV), were investigated by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) in untreated wastewater, autoclaved wastewater, and dechlorinated tap water stored at 4, 15, 25, and 37°C. Temperature, then matrix type, most greatly influenced SARS-CoV-2 RNA first-order decay rates ( k). The average T ₉₀ (time required for 1 log ₁₀ reduction) for RNA of SARS-CoV-2 ranged from 8.04 to 27.8 days in untreated wastewater, 5.71 to 43.2 days in autoclaved wastewater, and 9.40 to 58.6 days in tap water. The average T ₉₀ for RNA of MHV at 4 to 37˚C ranged from 7.44 to 56.6 in untreated wastewater, 5.58 to 43.1 days in autoclaved wastewater, and 10.9 to 43.9 days in tap water. There was no statistically significant difference between RNA decay characteristics of SARS-CoV-2 and MHV were identified; thus, MHV is suggested as suitable persistence surrogate. Decay rate constants for all temperatures were comparable across all matrices for both viral RNAs, except in untreated wastewater for SARS-CoV-2, which showed less sensitivity to elevated temperatures. Therefore, SARS-CoV-2 RNA is likely to persist long enough in untreated wastewater to permit reliable detection.

Highlights

• •

  Temperature most greatly influenced SARS-CoV-2 RNA first-order decay rates.

• •

  SARS-CoV-2 and MHV RNA decay characteristics were similar.

• •

  MHV is suggested as suitable persistence surrogate.

• •

  SARS-CoV-2 RNA is likely to persist long enough in wastewater to permit detection.