Since the beginning of the pandemic, nationwide wastewater monitoring for SARS-CoV-2 has made a decisive contribution to monitoring the incidence of infection. Wastewater monitoring has been carried out at TZW in Karlsruhe since 2020, most recently as part of the project 'Wastewater monitoring for epidemiological situation assessment' (AMELAG), so that 4.5 years of data are now available. These extensive data have helped to identify the potential of wastewater-based monitoring of Covid-19 infections.
Since summer 2020, TZW has been analysing wastewater samples from the Karlsruhe wastewater treatment plant for SARS-CoV-2 gene sequences. 400 samples from Karlsruhe were analysed using digital droplet PCR (ddPCR) and compared with official infection numbers. The data obtained are used to draw conclusions about trends in infection dynamics. Infection numbers have not been collected any more since summer 2023, but wastewater monitoring still allows reliable observation of the infection process. For example, high concentrations of SARS-CoV-2 were detected in the wastewater of Karlsruhe in early October 2024, reflecting the high level of illness at that time.
Over the years, wastewater monitoring has established itself as a reliable tool for early and reliable detection of trends in infection incidence. It can also be used to track the emergence and spread of new SARS-CoV-2 variants in the population. Wastewater monitoring is now being used in Germany to complement existing disease surveillance systems. Long-term data from the Karlsruhe wastewater treatment plant have contributed significantly to the acceptance of the method. The data for Karlsruhe and a large number of other WWTPs are published in the publicly available AMELAG weekly reports (https://edoc.rki.de/handle/176904/11665) and on the website www.infektionsradar.de.
This monitoring is an important complement to traditional health data, as it provides a comprehensive, population-based assessment of the infection situation at low cost and independent of individual testing. Wastewater monitoring provides valuable information on current Covid-19 cases, particularly in areas where official infection numbers are not regularly collected. The results are compared with data from existing disease surveillance systems and used to assess the situation.
The work at TZW shows how innovative and sustainable wastewater monitoring can contribute to strengthening public health. The system established at TZW offers many possibilities that go beyond just monitoring SARS-CoV-2. For example, other viruses such as influenza, noroviruses or antibiotic-resistant bacteria could also be detected to provide more comprehensive information on the spread of infectious agents in the population. Continued and expanded surveillance will strengthen preventive health care and help better manage future pandemics or outbreaks.