The value of sewage surveillance to provide new insights on the circulation of SARS-COV-2 and to reveal the true extent of the coronavirus pandemic at the national scale

Infection with SARS-CoV-2, the etiologic agent of the current COVID-19 pandemic, is accompanied by excretion of the virus in the feces. Therefore, we assume that the quantification of SARS CoV-2 in sewage allows the prevalence of infections in the population to be monitored by wastewater-based epidemiology, particularly when clinical trial capacity is limited. The overall objective of the CORONASTEP+ project is to determine to which extent SARS-CoV-2 is present in domestic wastewater and to determine how far wastewater monitoring can be used to
track and understand the circulation of SARS-CoV-2 nationally. For this purpose, we need to understand how the faecal shedding parameters (frequency, duration, magnitude) in (a)symptomatic individuals influence the
uncertainty and variability of the data collected in wastewater treatment plants, in order to assess the significance of the presence of the SARS-CoV-2 in wastewater. Moreover, knowing the infectious hazard of SARS-CoV-2
containing sewage is of critical importance. To achieve these goals, some specific methodological objectives must be met, such as the establishment and the validation of a concentration procedure adapted to enveloped viruses, the set-up of quantitative RT-PCR assays, the implementation of an infectivity assay using cell culture as well as a high throughput sequencing approach to solve the viral strains diversity and the emergence of new variants. The data collected during this study from a set of more than 100 samples could help policy-makers surround the advancement or setback of social distancing and quarantine efforts on the basis of prevalence estimates at the level of treatment plants.