Only a few more weeks until autumn is here. More wastewater monitoring should help to counter the feared corona wave. Because the wastewater provides relevant information days before the official figures.
This is not exactly how you imagine a treasure trove of data. An inconspicuous plastic bottle filled with a greenish-brown liquid: wastewater from a Berlin sewage treatment plant. However, researchers can glean a lot of information from what most people carelessly flush down the sink and toilet. For example, about pathogens like the corona virus. Infected people excrete this with their urine, faeces and probably also with their saliva.
“While environmental monitoring is still in its infancy in Germany, a new branch of industry is already emerging in the USA,” says molecular biologist Markus Landthaler from the Max Delbrück Center for Molecular Medicine (MDC) in Berlin. He talks about new start-ups that offer wastewater monitoring for municipalities, for example. Trends in infection waves can be read from the measured virus concentrations. And according to experts, much earlier than with registration numbers. Distortions caused by testing were also eliminated: while only some infected people go to the doctor or the test center, everyone has to go to the toilet.
Some countries have already taken advantage of this during the pandemic. Citizens in Austria and the Netherlands, for example, can use the Internet to see how the situation is developing regionally. There, wastewater is checked for Corona in many places. For the third autumn with Sars-CoV-2, it is also planned in Germany to monitor wastewater more intensively. According to the Federal Ministry of Health, the monitoring should be expanded to 150 locations – as a building block in the autumn plan.
As early as the end of July, the Sars-CoV-2 values in the wastewater at locations in southern Hesse were higher than they had ever been during the pandemic, says Susanne Lackner. According to the professor in the Department of Water and Environmental Biotechnology at the TU Darmstadt, it is a harbinger of what is imminent in a few weeks.
Lackner is involved in an EU-funded pilot project for wastewater monitoring at 20 locations nationwide. Another 28 are integrated through funding from the Federal Ministry of Education and Research. The expansion is to take place on the basis of these 48. Extra projects are already running in some federal states. “After 2.5 years of research, the technical part is no longer a problem,” says Lackner.
The analysis process differs somewhat from laboratory to laboratory, but according to experts it is not magic. “Any reasonably equipped laboratory could do this kind of investigation,” says molecular biologist Emanuel Wyler from Landthaler’s MDC working group.
In the security level 2 laboratory, dressed in a mask, protective overall and gloves, he allows you to look over his shoulder during the work steps. As a visitor you are not allowed to touch anything. Even if you can hardly get infected with Corona from sewage, it still contains other pathogenic viruses or bacteria.
For the past year and a half, wastewater samples from the capital have been scrutinized here in Berlin-Mitte, so far a total of 120. This July day – hot outside, nice and cool in the laboratory – is the last time. The researchers are no longer primarily concerned with current Sars-CoV-2 evidence, but with the bigger picture. Dozens of pathogens are in view. A diagnostics laboratory for Berliner Wasserbetriebe has taken on routine corona measurements.
Wyler first pours the wastewater sample into two cup-like containers to filter out coarse dirt. What remains is fairly clear water that smells slightly. Then the researcher adds tiny iron beads: “The pathogens contained in the wastewater bind to them,” says the researcher. Their genetic information is extracted using a centrifuge. Then a PCR test follows, just like with corona nose and throat swabs. This checks whether a pathogen is present and in what quantity.
It is not possible to find out in this way whether a single infected person is in a city of millions. However, depending on the measurement method and virus variant, the procedure is considered to be very sensitive: “In early 2020, we tested positive for wastewater in Leipzig with an incidence of five cases per 100,000 inhabitants,” says René Kallies from the Helmholtz Center for Environmental Research. At Omikron, Wyler speaks of a detection threshold at an incidence of around 50. Conversely, it should be considered: not all infected people excrete the same amount of virus. Wastewater monitoring therefore does not allow an incidence calculation.
It is often said that it is an early warning system. Expert Lackner quarrels with the term. “It’s not a method that predicts what’s coming.” Rather, one sees the current state. “The advantage is that the dynamics can be recorded very quickly. Wastewater data would help to finally get in front of the wave instead of just chasing after the development,” says the professor.
Increasingly occurring mutations are also recognizable. “We can detect the complete virus genome in the wastewater.” This could also give a better picture of the virus variants that occur. So far, analyzes have only been carried out on very few positive PCR smears. “So far we’ve been flying blind in Germany,” says Lackner.
Experts have repeatedly pointed out advantages that the procedure could bring compared to the previous data. The entire method is not new anywhere in the world. Other countries are more advanced, says Kallies: “In Bangladesh, for example, tests are carried out for up to 60 pathogens.”
Lackner even found an article from 1939 in which US experts describe the search for polio in sewage. Evidence came from monkeys that were given some of it and then fell ill.
In the pandemic, the clarification of concerns and legal questions and the negotiation of cost and responsibility issues took time in this country, insiders report. A researcher speaks of German thoroughness. There is a lack of pragmatism.
If there were a kind of weather report for the regional spread of Corona, for example, people could adapt their behavior, researchers argued. If the situation worsens, you can stay in the home office or opt for an FFP2 mask when shopping. But measures could also be derived – but that is a matter for politics. So far, no country has found an ideal way to deal with wastewater data, says Kallies. He does not fail to mention that the dirty water also contains sensitive information: With appropriate sampling, hotspot neighborhoods can be found.
The city of Cologne is one of the 20 pilot locations in the wastewater project. The first evaluations were already available there last autumn and winter. The head of the health department, Johannes Nießen, is convinced of the benefits as an additional indicator, as he says. The city was prepared earlier, also to decide on measures. “The costs are manageable at 5000 euros per month.”
Nießen, who is on the Federal Government’s Expert Council, refers to a graphic with two curves: the corona wastewater values are currently four to five days ahead of the reporting data, the summer wave is ebbing. With more locations involved nationwide, Nießen promises an even greater meaningfulness. According to him, the targeted 150 locations would cover a third of the population. They would be tested together – “anonymously when going to the toilet”.
However, a single sample in Wyler’s laboratory does not provide quick information about the situation, as the researcher says. It needs the context of the series of measurements to identify trends. For Wyler and his colleagues in basic research, the real work is still ahead anyway: evaluating data on the computer. Ultimately, her research is about understanding the diversity of viruses and bacteria throughout nature and recognizing as early as possible whether something could be dangerous for humans.
In the long term, the aim is to identify possible patterns in large amounts of data that allow, for example, predictions to be made about the course of disease waves, says Landthaler. The ideas go beyond Corona: will we eventually receive daily reports on the spread of flu, respiratory diseases such as RSV and gastrointestinal infections? Antibiotic-resistant germs are also an issue. Likewise, other environmental sources, the study of which could provide further insights, such as mosquitoes.
But everything in its time. In Germany it is still unclear what exactly autumn will bring in terms of wastewater monitoring. On request, the Federal Ministry of Health informed that the design of the system was still under development. A common IT data structure should therefore be ready by September. How many more locations – and which ones – will actually be connected in the next few weeks? Still open.
