Evaluation of coronavirus decay in French coastal water and application to SARS-CoV-2 risk evaluation using Porcine Epidemic Diarrhea Virus as surrogate.

SARS-CoV-2 in infected patient mainly display pulmonary and oronasal tropism however, the presence of the virus has also been demonstrated in stools of patients and consequently in wastewater treatment plant effluents, questioning the potential risk of environmental contamination (such as seawater contamination) through inadequately treated wastewater spill-over into surface or coastal waters. The environmental detection of RNA alone does not substantiate risk of infection, and evidence of an effective transmission is not clear where empirical observations are lacking. Therefore, here, we decided to experimentally evaluate the persistence and infectious capacity of the Porcine epidemic diarrhea virus (PEDv), considered as a coronavirus representative model and SARS-CoV-2 surrogate, in the coastal environment of France. Coastal seawater was collected, sterile-filtered, and inoculated with PEDv before incubation for 0-4 weeks at four temperatures representative of those measured along the French coasts throughout the year (4, 8, 15, and 24{degrees}C). The decay rate of PEDv was determined using mathematical modeling and was used to determine the half-life of the virus along the French coast in accordance with temperatures from 2000 to 2021. We experimentally observed an inverse correlation between seawater temperature and the persistence of infectious viruses in seawater and confirm that the risk of transmission of infectious viruses from contaminated stool in wastewater to seawater during recreational practices is very limited. The present work represents a good model to assess the risk of transmission of not only SARS-CoV-2 but may also be used to model the risk of other coronaviruses, specifically enteric coronaviruses. ImportanceThis present work is a follow up addressing the question of the persistence of coronavirus in marine environment owing to the fact that SARS-CoV-2 is regularly detected in wastewater treating plan and the coastal environment is particularly at risk since it is subjected to increasing anthropogenic pressure and is the final receiver of surface waters and treated or sometimes insufficiently depurated waste waters. Our findings are of interest to researchers and authorities seeking to monitor SARS-CoV-2 and also enteric coronaviruses in the environment, either in tourist areas or in regions of the world, where centralized systems for wastewater treatment are not implemented, and more broadly, to the scientific community involved in "One Health" approaches.