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Hamburg wastewater treatment plant Köhlbrandhöft
Photo: Bodo Marks / picture alliance / dpa
In spring 2020, when the corona pandemic spread across the world, scientists were looking for an early warning system for the virus around the world.
One approach seemed particularly promising: the analysis of wastewater.
Because from the traces of the virus genome, which every infected person excretes and flushes through the toilet into the sewer, outbreaks of Sars-CoV-2 could perhaps even be recognized before the infected themselves know anything about the virus.
In Germany, some research groups are working on molecular analysis technology, which is basically based on the well-known PCR tests.
But while a number of countries such as the Netherlands, Switzerland or Australia are already uploading wastewater data on infection occurrences to dashboards, in Germany the interest from politics and administration in the technology seems to be minimal.
That could change now, the European Union is putting Germany under pressure.
In March, the EU Commission issued a recommendation suggesting that sewage monitoring should also be used as an instrument in the joint fight against the virus.
Wastewater analyzes from 56 cities
Member States should set up a wastewater monitoring system by October 1, 2021 at the latest, which will cover a significant part of the population.
To this end, the sewage treatment plants for large cities with more than 150,000 inhabitants are to be sampled and analyzed at least twice a week.
For Germany, such a system would have to be implemented in 56 cities.
"A huge task," says Jörg Drewes from the Technical University of Munich.
He has developed a system for wastewater monitoring in several cities, including in Berchtesgadener Land, where he forwarded wastewater data directly to the crisis team.
SPIEGEL:
Mr. Drewes, you have been working on a wastewater monitoring system in Berchtesgadener Land for months.
When will something like this come on a larger scale for Germany?
Drewes
: It's a tragedy.
At the federal level
We are not getting a step further, although scientifically reliable data are available that corona wastewater monitoring can be a robust diagnostic tool in combating pandemics.
SPIEGEL:
What is the problem?
Drewes
: Mainly in the political implementation.
Weeks have passed since the EU Commission's recommendation.
But the Federal Ministry of Health and the Federal Environment Ministry are still debating who is responsible and how the concept could be implemented.
Many nations have long been much further ahead than Germany, and good experiences have been made.
SPIEGEL:
In the meantime, more and more rapid tests are available that are also supposed to shed light on the number of unreported infections - just like wastewater monitoring. Would the system still be of use to us in the current coronavirus situation?
Drewes
: Wastewater monitoring does much more than just estimate the number of unreported cases.
Rapid tests cannot tell you whether the infections are rising or falling - days before the official RKI figures.
After the Easter holidays, we saw again how little informative value even the officially reported number of cases had, because there were delays due to fewer tests and lower capacities in the health authorities.
My concern is that we will not have such a system in the municipalities until the pandemic is over - if at all.
Then we would have wasted an enormous opportunity in fighting the pandemic.
SPIEGEL:
Do you have any hopes that the recommendation from Brussels will change anything?
Drewes
: At least on the political side, it triggered an awareness of the topic that wasn't there before.
It's good.
But it seems to me that people in Berlin were surprised that the matter was given such great relevance at the European level.
The current approach in Germany is more like looking for reasons why something like this cannot work in Germany.
SPIEGEL:
What do you mean by that?
Drewes
: As usual in Germany, you follow the standard procedure for introducing a new standard. As a federal authority, the RKI, for example, now feels it is obliged to develop instructions for handling data from wastewater monitoring based on the EU recommendation, which work for all health authorities in the state and are, so to speak, generally applicable. According to the rules is fine under normal circumstances, but it is not effective in a pandemic. In addition, the requirements in the offices and crisis teams in the federal states are very different, some work fully networked digitally, others are still at the beginning of the topic, not to mention personnel bottlenecks. That's why people quickly say: This cannot be built up in this country.
SPIEGEL
: How do you think one should proceed?
Drewes
: We should proceed more pragmatically and see such a monitoring system as an opportunity - it doesn't have to be implemented across the board with binding norms and a legal framework.
But wherever the conditions are right and municipalities are willing to use this system, we should provide assistance.
SPIEGEL
: But isn't it problematic if different methods are used in the municipalities?
Drewes
: For this type of diagnosis, it is not a problem that the results of the individual municipalities are not yet fully comparable.
It is important to always work with the same method in one place and in a municipality.
Sure, we are still in the development process to a certain extent while we are already working with the system and not all questions have been clarified.
But in this crisis situation we shouldn't wait until we have fully validated everything.
In the laboratories we have quality requirements that we check before we report a positive result.
Quality standards are adhered to and the data that we publish is reliable.
SPIEGEL:
How big is the effort for the operators of sewage treatment plants?
Drewes
: This is relatively easy for a general impression of the infection process. Sampling on site is automated, which is routine at all sewage treatment plants. The municipalities are often willing to provide some working time for their sewage treatment plant staff. In Berchtesgadener Land we also use an app that every municipality can use to enter data during sampling. This means that the data is transmitted directly to a central dashboard in the crisis team. There we also feed in our laboratory results and via an interface to the contact tracking software SORMAS, which is also used by many health authorities, the corona results in the wastewater can be shown georeferenced with the local case numbers and the data from the sewer system. This does not burden the staff of the health authorities.And the decision-makers immediately see the findings on a monitor.
SPIEGEL:
That sounds simple.
Then what's the problem?
Drewes:
There is no help for municipalities on how to develop something like that.
And at the moment the costs are stuck with the municipalities.
In Berchtesgaden, the district office commissioned a programmer to set up the necessary interfaces.
But it is ineffective if every county has to do it all over again.
Here, for example, the RKI would be asked to offer this service once for everyone.
And every district or every city that wants to introduce monitoring can then use this uniform interface.
SPIEGEL
: How high are the costs?
Drewes
: The EU estimates the costs at 25,000 euros per sewage treatment plant per year with two samples per week.
This is consistent with our experience of around 250 euros per wastewater sample.
In order to map 60 percent of the German population in a monitoring system, 450 sewage treatment plants would have to be sampled.
Of course, the question of who will do this still needs to be clarified.
When it comes to health care issues, I see the federal government as responsible.
But many municipalities are ready to make a contribution, so the money alone is not an argument for me.
Incidentally, the EU has also offered to support such a system financially.
SPIEGEL:
Could you take action at an early stage based on your data?
Drewes
: The sensitivity of our method is 1,000 per million.
That means, I recognize 1,000 infected people in a city of over a million people.
But of course you cannot order any measures on the basis of wastewater monitoring alone, that is not possible from a purely legal point of view, that must always be accompanied by individual tests.
In Australia, where wastewater monitoring is used across the board, the system is now the decisive measure for the test strategy with the very low number of cases there.
Individual PCR tests are only started again when the frequency of positive findings in the wastewater exceeds a certain level.
We could do that in Germany in the same way.
SPIEGEL:
Isn't that more precise?
Drewes
: If I need higher-resolution data because the infection rate is perhaps just as high as it is now or is developing differently locally, I can also take samples in the sewer system or pumping stations and receive data from individual parts of the city
SPIEGEL:
Can such monitoring be used everywhere?
Drewes
: In principle, yes, but certain boundary conditions have to be met.
For example, the number of sampling points to take a representative sample of a city's sewage network must remain manageable.
We also need further data from the municipalities, which ideally should all be digitally available to the crisis teams.
Since these conditions cannot be met in a short time everywhere, we will not be able to use this monitoring in some districts or cities, or only to a very limited extent
SPIEGEL:
What do we do with a monitoring network like this when the pandemic is over?
Is it useless then?
Drewes
: Not at all. If we manage to build such a system, we have a much better chance of doing better in future pandemics. Such a network could also be used for other analysis methods, they don't even have to be viruses. Think antibiotic resistance or drugs. We are also planning a database based on simple tests that will act as a kind of memory of the pandemic. This could, for example, document genetic changes in viruses and identify when and where new mutations could be detected.