Rapid Assessment of SARS-CoV‑2 Transmission Risk for Fecally Contaminated River Water

Following the outbreak
of severe acute respiratory syndrome coronavirus
(SARS-CoV-2), airborne water droplets have been identified as the
main transmission route. Identifying and breaking all viable transmission
routes are critical to stop future outbreaks, and the potential of
transmission by water has been highlighted. By modifying established
approaches, we provide a method for the rapid assessment of the risk
of transmission posed by fecally contaminated river water and give
example results for 39 countries. The country relative risk of transmission
posed by fecally contaminated river water is related to the environment
and the populations’ infection rate and water usage. On the
basis of in vitro data and using temperature as the primary controller
of survival, we then demonstrate how viral loads likely decrease after
a spill. These methods using readily available data suggest that sewage
spills into rivers within countries with high infection rates could
provide infectious doses of >40 copies per 100 mL of water. The
approach,
implemented in the supplementary spreadsheet, can provide a fast estimate
of the upper and lower viral load ranges following a riverine spill.
The results enable evidence-based research recommendations for wastewater
epidemiology and could be used to evaluate the significance of fecal–oral
transmission within freshwater systems.