Wastewater monitoring to detect SARS-CoV-2 is becoming increasingly important. Local wastewater testing has been carried out since the pandemic emerged in 2020. In spring 2021, the European Commission confirmed its recommendation to introduce systematic wastewater monitoring of SARS-CoV-2 and its variants in all EU Member States. Waste-water-based epidemiology (WBE) offers great advantages, especially in metropolitan areas where the virus can spread rapidly.
A research team (see overview of partners*) has now confirmed the great potential of wastewater monitoring as an early warning system for metropolitan areas using the example of the city of Munich.
The one-year follow-up study, which started in April 2020, is one of the first and longest investigations to track the SARS-CoV-2 RNA viral load in wastewater worldwide and especially in Germany. The results have now been published in the journal Science of the Total Environment. Under the leadership of the Tropical Institute at the LMU Hospital Munich, the Virology Department of the Max von Pettenkofer Institute, the Gene Center of the LMU, the Munich Municipal Drainage Department, the Munich Fire Department, the Health Department of the City of Munich and the Infectiology Task Force of the Bavarian State Office for Health and Food Safety (LGL) participated in the study. The research was funded by the Bavarian Ministry of Science and the Arts. Science Minister Bernd Sibler emphasizes the practical relevance of the study: "It makes a valuable contribution to taking further steps towards the normalization of public life despite the ongoing corona pandemic. That is why we have supported the study Prospective COVID-19 Cohort Munich - KoCo19 with around one million euros."
Spread of SARS-CoV-2 detected weeks earlier by wastewater analysis than in official reporting figures
In their study in the Munich area, the scientists have been collecting weekly wastewater samples at six locations in the Munich city area for over a year since the beginning of April 2020. The samples were analyzed in the laboratory using RT-PCR (reverse transcription polymerase chain reaction) and genome sequencing to measure the spread of SARS-CoV-2 in Munich over time and space. By decoding the genetic material using the sequencing of isolated viral RNA, the researchers also obtained information on whether variants of concern (VOCs) were present in the samples.
The results showed that the SARS-CoV-2 RNA load detected in the samples corresponded well with the official data on the 7-day incidence in the respective urban areas. Study leader PD Dr. med. Andreas Wieser from the Tropical Institute at the LMU Hospital reports: "The viral load measured in the wastewater allowed us to determine the local incidence of SARS-CoV-2 three weeks earlier than in the authorities' reporting figures, which are based on the analysis of respiratory swabs. In addition, we were able to detect the increasing spread of the virus variant B.1.1.7 (alpha) in the Munich population as early as the beginning of January 2021, weeks before it could be detected in relevant numbers by sequencing swab samples from patients in Munich."
Overall, the study confirms the potential of wastewater monitoring as an early warning system for the SARS-CoV-2 pandemic and the advantages compared to mass testing using swabs. This is particularly true with regard to the spread of virus variants of concern in the local population. In addition, wastewater sampling has fewer biases, e.g. due to changes in sampling rules or reporting routes, than statistics based on swab/reporting data.
Original publication:
Rubio-Acero R, Beyerl J, Muenchhoff M, Sancho Roth M,Castelletti N, Paunovic I, Radon K, Springer B, Nagel C, Boehm B, Böhmer M, Graf A, Blum H, Stefan S, Keppler O, Osterman A, Khan Z, Hölscher M, Wieser A
Spatially resolved qualified sewage spot sampling to track SARS-CoV-2 dynamics in Munich - One year of experience, Science of The Total Environment, Volume 797, 2021, 149031, ISSN 0048-9697, https://doi.org/10.1016/j.scitotenv.2021.149031
*Partner of the study:
- Lead: Tropical Institute (Department of Infectious Diseases and Tropical Medicine), LMU Klinikum München
- Center for International Health (CIH), LMU Klinikum München
- German Center for Infection Research (DZIF), Munich site
- Munich Municipal Drainage
- Munich Fire Department
- Health Department of the City of Munich
- Task Force Infectiology, Bavarian State Office for Health and Food Safety (LGL)
- Gene Center of the LMU Munich
- Max von Pettenkofer Institute for Virology, LMU
Funding:
The study was funded by the Bavarian Ministry of Science and Art and the LMU Munich Hospital.
The study is accompanying and complementary to the KoCo19 study group (Representative SARS-CoV-2 Study in Munich, "Prospective COVID-19 Cohort Munich - KoCo19"), with the participation of: Helmholtz Zentrum München, University of Bonn, University of Bielefeld, Federal Ministry of Education and Research (Project01KI20271) and the Bundeswehr Institute of Microbiology (Medical Biodefense Research Program) as well as the BMBF initiative "NaFoUniMedCovid19" (01KX2021), subproject B-FAST.
