Since November 2021, the SES company laboratory had taken daily samples from the inflow in the main sewage treatment plant in Stuttgart-Mühlhausen. Statisticians have now evaluated the data and found connections between the viral load and the 7-day incidence.
dr Till Heinsohn, head of the Economics and Surveys department at the Statistical Office, said on Thursday, July 14: “We see that the viral load in the wastewater is about eight days ahead of the 7-day incidence. So we have an additional early warning system here. To describe the actual situation, however, further indicators are required, such as the occupancy of hospital beds, the load on emergency rooms and medical practices, or representative sample surveys.” And further: “The measurements allow conclusions to be drawn about developments. Continuous observation and classification are important here.”
According to the processing by the Statistical Office, the individual waves were already apparent in the wastewater at an early stage, even before they became visible through PCR tests.
Prof. Stefan Ehehalt, head of the health department, says about the study: “We see that the incidence determined by PCR tests is less and less capturing the infection process. There is a great deal of interest among the public and also in the healthcare sector to know how pathogens spread. The wastewater analysis provides orientation, regardless of the test behavior or the type of test used. Public health officers therefore expressly recommend such a wastewater monitoring for Corona.”
Peter Schilling, head of the central laboratory for city drainage: “In our investigations into the corona load, we use a somewhat simplified PCR method. A well-known manufacturer of laboratory and online measuring devices has exclusively provided us with the equipment for this. The 24-hour mixed sample of the main sewage treatment plant inflow is analyzed every day. In addition to the obligatory Ct value, the measurement also gives a concentration value in GU/ml. This is then extrapolated to a daily load with the daily amount of wastewater, normalized to 100,000 inhabitants and compared to the 7-day incidence curve.”
In addition, since the beginning of March 2022, the State Health Office has been examining the wastewater in the inflows of the Stuttgart-Mühlhausen and Tübingen sewage treatment plants twice a week. It participates with 18 other locations in the nationwide project ESI-CorA (Emergency Support Instrument).
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