Capturing the SARS-CoV-2 infection pyramid within the municipality of Rotterdam using longitudinal sewage surveillance

ABSTRACT

BackgroundDespite high vaccination rates in the Netherlands, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continues to circulate. Longitudinal sewage monitoring was implemented along with the notification of cases as two parts of the surveillance pyramid to validate the use of sewage surveillance for monitoring SARS-CoV-2, as an early warning tool, and to measure the effect of interventions. MethodsSewage samples were collected from nine neighborhoods from September 2020 to November 2021, and compared with reported cases. Comparative analysis and modeling were performed to understand the correlation between wastewater and case trends. FindingsUsing high resolution sampling, normalization of wastewater SARS-CoV-2 concentrations and normalization of reported positive tests for testing delay and intensity, the incidence of reported positive tests could be modeled based on sewage data, and trends in both surveillance systems coincided. The high collinearity implied that high levels of viral shedding around the onset of disease largely determines SARS-CoV-2 levels in wastewater and the observed relation was independent of SARS-CoV-2 variants and vaccination levels. InterpretationWastewater surveillance can accurately display SARS-CoV-2 dynamics for small and large locations, and is sensitive enough to measure small variations in the number of infected individuals within or between neighborhoods. With the transition to a post-acute phase of the pandemic, continued sewage surveillance can help to keep sight on reemergence, but continued "pyramid" validation studies are needed to assess the predictive value of sewage surveillance with new variants. FundingHorizon H2020, Adessium Foundation, STOWA, TKI, Ministry of Health, Welfare and Sport