EU puts pressure on
Corona early detection: What wastewater analyzes can do
Corona can also be detected in people’s stools. So it makes sense to get an idea of the situation by means of wastewater analyzes. But it is still not working across the board. Despite pressure from the EU.
How strict the corona restrictions are in a region in Germany depends on the infection rate. The authorities assess the situation based on the number of positive corona tests, among other things.
There is another method that offers advantages. Wastewater analyzes can give a good overview of how widespread the pathogen is in the population. But so far the system is not yet mature enough.
Although the coronavirus mainly affects the respiratory tract, particles of the pathogen can also be detected in the stool. If the EU and the Federal Government have their way, the examination of wastewater should therefore become an important instrument in the early detection and localization of the infection process.
According to the Federal Ministry of Research, this would have some decisive advantages over conventional assessment of the situation via tests. The total population, including those infected with asymptomatic disease, could be recorded. “Regardless of the willingness to be tested or the existing test capacities,” said a ministry spokesman when asked by the German press agency. Such wastewater analyzes thus shed light on the dark field of infections.
In addition, in contrast to the test results, these surveys are largely independent of the weekly and holiday rhythm and can estimate the dynamics of the infection process around ten days in advance of the clinical number of cases.
The EU puts pressure on the nation states. A recommendation by the Commission in March states: “The member states are urged to set up a national wastewater monitoring system” for early detection of corona as soon as possible, but no later than October 1, 2021. ” Monitoring is an inexpensive, fast and reliable source of information about the spread of the virus. The EU recommendation is not legally binding.
In Germany, several research institutions are working on the topic, and samples are being taken at dozen of sewage treatment plants. But so far, according to researchers, the local corona situation has only been insufficiently assessed with the method. “Individual measurements are currently still fluctuating too strongly to actually provide a basis for political decisions,” explains a spokeswoman for the Helmholtz Center for Environmental Research (UFZ) in Leipzig, whose researchers are largely working on the investigation method. Methodological improvements are therefore necessary. Currently, only trends in the infection process can be shown.
In addition, the absolute measured values of the wastewater investigations have so far not allowed any comparisons between different locations, as the UFZ spokeswoman explains. Because the sampling, measuring and analysis processes have not yet been standardized. A uniform standard is still being developed and is to be developed in the future by the German Institute for Standardization (DIN).
The German Association for Water Management, Wastewater and Waste (DWA) announced on request that wastewater tests are basically suitable for early corona detection. With such investigations it was possible to localize regional outbreaks in Berchtesgaden (Bavaria), for example, and take appropriate steps. Researchers found the British mutant in the sewage of a Swiss ski resort before the Federal Office of Public Health could confirm such cases.
Nevertheless, the method is unlikely to be a silver bullet. Wastewater analyzes as an early warning and all-clear system would have to be used in addition to the test strategy, writes the Ministry of Research.
The specific number of infected people cannot yet be derived from the samples, says Swetlana Rot, who examines the samples from four locations in the state at the Saxony-Anhalt State Office for Environmental Protection. Likewise, the mutant determination is not yet fully developed. “We get everything in the water – all the RNA snippets. We can quickly determine whether this is Covid-19, but determining exactly which mutant it is is difficult. “