When the corona numbers in the municipality of Saaldorf-Surheim in Berchtesgadener Land skyrocketed in March 2021, the local crisis management team knew what to do. The team concentrated on the 2,900 residents of the Surheim district, identified contact persons, and ordered quarantine. The 1300 citizens in Saaldorf, on the other hand, remained unmolested, although the official corona numbers for both districts are combined. But there is one crucial difference: the two districts each have their own sewage treatment plant. At that time, there were plenty of traces of the corona virus in Surheim's wastewater, but none in Saaldorf.
Jörg Drewes, Professor of Urban Water Management at the Technical University of Munich, has plenty of stories like this in store. They deal with corona outbreaks that could be traced back to a boarding school and a steel mill based on the sewage; of targeted controls that only took place on the basis of wastewater analyzes and uncovered asymptomatic cases. At one point, the investigations even uncovered an unannounced street party. Many of the participants were infected, their excrement was noticed in the close-meshed monitoring network that Drewes had set up in Berchtesgadener Land: Since November 2020, he has had 40 milliliters of wastewater taken twice a week in the region’s sewage treatment plants and searched for SARS-CoV-2 . The Corona crisis team then uses this data for its work.
Only a fraction of the approximately 10,000 sewage treatment plants
A form of control is possible because infected people swallow their own saliva and thus coronaviruses, and then excrete them again.
Whether they develop symptoms or not.
According to Drewes, even with an incidence of less than twenty infections per 100,000 inhabitants, the virus snippets in the wastewater can be reliably evaluated.
The number of infections can then be deduced from the concentration.
This works regardless of the willingness to undergo a test.
Everyone has to go to the toilet, so no one can avoid that, Drewes clarifies.
Also on weekends and public holidays.
This frees the wastewater analysis from the typical fluctuations in the official corona numbers. Since the signals from the cloaca are sometimes days ahead of the official surveys, the procedure is suitable for an early warning system. When the rest of Germany flew blindly towards the latest corona wave, Drewes could see it rolling in the faeces shortly after the holidays. He describes the project in Berchtesgadener Land as a "prime example for the efficient integration of innovations into the crisis management of the authorities". In other words, it's a huge exception.
Although the European Commission already recommended to its member states in March 2021 to examine the waste water across the board for SARS-CoV-2 from October, Germany is far from it. There is no lack of research, there are numerous projects. "As part of this, 139 sewage treatment plants and sewer sites were or are being sampled," says Sabine Thaler from the German Association for Water Management, Wastewater and Waste. Although the wastewater from 15 million people was analyzed, the selection corresponds to only a fraction of the approximately 10,000 sewage treatment plants in Germany.
Elsewhere you are further.
The Netherlands publishes data on Sars-CoV-2 particles in wastewater every day.
A map shows that the western part of the country is particularly affected.
There are similar efforts in five other EU countries, as well as in Tyrol and Catalonia.
Pilot projects are running in eight countries, Germany is lagging behind.
However, the statement that one had once again overslept a little would not go far enough.
In fact, the process still raises a number of questions.