Wastewater also discovers new corona mutations

The epidemiological situation is to be kept under control. In order to be able to assess the development of the Corona pandemic as well as possible, the canton of Zurich would like to have access to meaningful and reliable data. Until now, those responsible have had access mainly to reporting data from laboratories, hospitals and other health care facilities. However, according to the Zurich Health Directorate, the reliability of these data depends mainly on the testing behavior of the population. Since rapid tests have recently become available, this may have changed, according to the authority.

Wastewater tests as a supplement

With wastewater being tested for SARS-CoV-2 virus by the Eawag Water Research Institute (see below), there is another option for assessing the course of the epidemic: the method has the advantage that it is independent of the testing behavior of the population. The disadvantage, he said, is that it is somewhat less precise in terms of quality. Together with the data from the test results, however, a more meaningful picture of the situation is obtained, according to the Canton of Zurich Health Department. Wastewater monitoring can also be used to detect new virus mutations or other emerging pathogens. Smallest amounts in the catchment area of a wastewater treatment plant are sufficient for this. In the meantime, the wastewater measurements have progressed so far that concrete statements about the epidemic course are possible.

Monitoring extends tests to more ARAs

The Eawag Water Research Institute and the École polytechnique fédérale de Lausanne (EPFL), with the support of the Directorate of Public Health, have been working on the method for the wastewater treatment plant of the City of Zurich ("Werdhölzli WWTP") since the beginning of the pandemic. The institutes have been publishing corresponding data for some time. The Health Directorate would now like to continue the wastewater measurement and apply it more broadly. The tests are to be extended to other wastewater treatment plants. The Cantonal Laboratory, which is affiliated to the Health Directorate, is therefore continuing to develop wastewater monitoring in close cooperation with Eawag. This system is being implemented in coordination with the canton of Grisons, which has already introduced such monitoring.

First results in June

It is planned that the first results of the cantonal wastewater monitoring will be available in June 2021. According to the Zurich Health Directorate, the measuring system is also suitable for use after the Corona pandemic: it could continue to be used as an early detection indicator for other pathogens.

AbwasSARS-CoV-2" project

In February 2021, Eawag launched the "AbwasSARS-CoV-2" project together with the FOPH (Link to video from minute 15:36). In this project, raw sewage is collected daily from six wastewater treatment plants (see map below) and analyzed for RNA of SARS-CoV-2. Covid-19 is known to be a respiratory disease, but a significant proportion of people excrete the genetic material of the virus (RNA) in their stool. Eawag writes: "By collecting and analyzing wastewater samples for this genetic material, we can determine whether and to what extent people in the catchment area of a wastewater treatment plant are infected with the virus. Because of the time lag between symptoms and confirmed test results, we may be able to detect the virus circulating in communities via wastewater before clinical case data are available."

According to Eawag, in the "AbwasSARS-CoV-2" project the measurement series are usually updated once or twice a week. The following links take you to the graphs:

Overview all wastewater treatment plants

Altenrhein ARA Altenrhein

Chur ARA Chur

Laupen ARA Sensetal

Lausanne STEP Vidy

Lugano CDA Lugano

Zurich ARA Werdhölzli