Viral RNA in City Wastewater as a Key Indicator of COVID-19 Recrudescence and Containment Measures Effectiveness

Abstract

In recent years, and more specifically at the beginning of the COVID-19 crisis, wastewater surveillance has been proposed as a tool to monitor the epidemiology of human viral infections. In the present work, from July to December 2020, the number of copies of SARS-CoV-2 RNA in Marseille’s wastewater was correlated with the number of new positive cases diagnosed in our Institute of Infectious Disease, which tested about 20% of the city’s population. Number of positive cases and number of copies of SARS-CoV-2 RNA in wastewater were significantly correlated (p = 0.013). During the great epidemic peak, from October to December 2020, the curves of virus in the sewers and the curves of positive diagnoses were perfectly superposed. During the summer period, the superposition of curves was less evident as subject to many confounding factors that were discussed. We also tried to correlate the effect of viral circulation in wastewater with containment measures, probably the most unbiased correlation on their potential inflection effect of epidemic curves. Not only is this correlation not obvious, but it also clearly appears that the drop in cases as well as the drop in the viral load in the sewers occur before the containment measures. In fact, this suggests that there are factors that initiate the end of the epidemic peak independently of the containment measure. These factors will therefore need to be explored more deeply in the future.

Surveillance of SARS-CoV-2 RNA in open-water sewage canals contaminated with untreated wastewater in resource-constrained regions

“…The changes in the reported number of confirmed COVID-19 cases in the communities around the locations where both the sample sets were collected during the first wave in 2020 and in the second wave in 2021 both in the earlier and later phases seem to align well with the viral load detected in the corresponding wastewater samples. Recent reports have also stated similar correlations between viral RNA in city wastewater collected from large wastewater treatment plants or sewer networks and the total number of reported or new positive cases observed in the hospitals in the city [36, 37]. The increase in COVID-19 patients in the area of sampling may be reflected by the increase in coronavirus viral RNA levels detected in the canal water.…”

Sewage Systems Surveillance for SARS-CoV-2: Identification of Knowledge Gaps, Emerging Threats, and Future Research Needs

“…In accordance with these hypothesis, Wurtz et al pointed to two episodes of rain (September 19 to 22 and November 7 to 8) in their sewage monitoring for SARS-CoV-2. Surprisingly, they opined that the quantity of viruses did not fall during the first episode, but possibly with the second [ 190 ].…”

SARS-CoV-2 Wastewater Surveillance for Public Health Action

“…Wastewater treatment plants can serve sewersheds containing thousands to millions of people, depending on their size, and measurements of SARS-CoV-2 RNA in wastewater collected at the plant can provide insight into infection burdens in the sewershed population. Several cities are now reporting correlations between SARS-CoV-2 concentrations at wastewater treatment plants and diagnosed COVID-19 cases in the sewershed service area (7,9,14,(22)(23)(24).…”

“…Although the importance of seeing the application of wastewater SARS-CoV-2 data in public health practitioners' own communities cannot be overstated, providing clear case examples of other community applications and perspectives across different jurisdictions and areas is recommended to improve confidence in these novel surveillance data. As the field of wastewater surveillance advances, a growing body of literature describes examples of use cases (9,22,24,31). In addition, retrospective analyses and peer-reviewed reporting of case studies should be encouraged as a means of increasing decision-making confidence for future related scenarios.…”