No evidence for environmental transmission risk of SARS-CoV-2 in the UK’s largest urban river system: London as a case study

Abstract

The presence of SARS-CoV-2 in untreated sewage has been confirmed in many countries but its incidence and infection risk in contaminated freshwaters is still poorly understood. The River Thames in the UK receives untreated sewage from 57 Combined Sewer Overflows (CSOs), with many discharging dozens of times per year. We investigated if such discharges provide a pathway for environmental transmission of SARS-CoV-2. Samples of wastewater, surface water, and sediment collected close to six CSOs on the River Thames were assayed over 8 months for SARS-CoV-2 RNA and infectious virus. Bivalves were sampled as sentinel species of viral bioaccumulation. Sediment and water samples from the Danube and Sava rivers in Serbia, where raw sewage is also discharged in high volumes, were assayed as a positive control. We found no evidence of SARS-CoV-2 RNA or infectious virus in UK samples, in contrast to RNA positive water and sediment samples from Serbia. Furthermore, we show that infectious SARS-CoV-2 inoculum is stable in Thames water and sediment for < 3 days, while RNA remained detectable for at least seven days. This indicates that dilution of wastewater likely limits environmental transmission, and that infectivity should be embedded in future risk assessments of pathogen spillover.

Disinfection and decontamination in the context of SARS‐CoV‐2‐specific data

“…The latter study did not include an assessment for viable virus. Wastewater as a potential source or at least an indicator of disease prevalence is well studied 43 . It is reassuring that both proximal and distant wastewaters do not yield SARS‐CoV‐2 in culture, even though viral genome may be abundantly evident 44,45 .…”

“…Wastewater as a potential source or at least an indicator of disease prevalence is well studied. 43 It is reassuring that both proximal and distant wastewaters do not yield SARS-CoV-2 in culture, even though viral genome may be abundantly evident. 44,45 The latter provides some reassurance that decontamination of such fluids is not logistically required.…”

Detection of the SARS-CoV-2 Delta Variant in the Transboundary Rivers of Yunnan, China

“…The infectious potential of SARS-CoV-2 in wastewater, freshwater, and seawater is reported to be maintained for <4 days. 22 , 24 , 25 However, the potential viral transmission risks via the fecal–oral route and/or aerosolization of SARS-CoV-2 contaminated waters remain poorly understood. The World Health Organization (WHO) has emphasized the need to explore the presence of SARS-CoV-2 in environmental matrices, including wastewater and surface water.…”

“…Consequently, the genetic signal of SARS-CoV-2 has been extensively detected in untreated and treated wastewater and sludge samples from WWTPs, − hospitals, isolation sites, aircraft, airports, university campus dormitories, and the Tokyo 2020 Olympic and Paralympic Village as well as natural water bodies, such as rivers, , seawater, and groundwater, in multiple countries and regions (Table S1). The infectious potential of SARS-CoV-2 in wastewater, freshwater, and seawater is reported to be maintained for <4 days. ,, However, the potential viral transmission risks via the fecal–oral route and/or aerosolization of SARS-CoV-2 contaminated waters remain poorly understood. The World Health Organization (WHO) has emphasized the need to explore the presence of SARS-CoV-2 in environmental matrices, including wastewater and surface water.…”