Decay of infectious SARS-CoV-2 and surrogates in aquatic environments

The introduction of SARS-CoV-2 containing human stool and sewage into water bodies may raise public health concerns. However, assessment of public health risks by faecally contaminated water is limited by a lack of knowledge regarding the persistence of infectious SARS-CoV-2 in water. In the present study the decay rates of viable infectious SARS-CoV-2 and SARS-CoV-2 RNA were determined in river and seawater at 4 and 20 degrees C. These decay rates were compared to S. typhimurium bacteriophage MS2 and pepper mild mottle virus (PMMoV). Persistence of viable SARS-CoV-2 was temperature dependent, remaining infec-tious for significantly longer periods of time in both freshwater and seawater at 4 degrees C than at 20 degrees C. T 90 for infectious SARS-CoV-2 in river water was 2.3 days and 3.8 days at 20 degrees C and 4 degrees C, respectively. The T 90 values were 1.1 days and 2.2 days in seawater at 20 degrees C and 4 degrees C, respectively. In contrast to the rapid inac-tivation of infectious SARS-CoV-2 in river and sea water, viral RNA was relatively stable. The RNA decay rates were increased in non-sterilised river and seawater, presumably due to the presence of microbiota. The decay rates of infectious MS2, MS2 RNA and PMMoV RNA differed significantly from the decay rate of SARS-CoV-2 RNA, suggesting that their use as surrogate markers for the persistence of SARS-CoV-2 in the environment is limited. (c) 2021 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY license ( http://creativecommons.org/licenses/by/4.0/ )

Automated summary

The study found that the persistence of infectious SARS-CoV-2 in water was temperature dependent, with the virus remaining infectious for longer periods in colder temperatures. In contrast, viral RNA was relatively stable. The use of surrogate markers such as bacteriophages MS2 and PMMoV RNA showed significant differences in decay rates compared to SARS-CoV-2 RNA, limiting their effectiveness in assessing the persistence of the virus in the environment.