The federal government’s Covid numbers are also published every Tuesday. But how reliable are these numbers? Because since January 1, the federal government has no longer paid for corona tests. The test numbers collapsed immediately. The epidemiologist Tanja Stadler heads the scientific group that supports the federal government on pandemic issues. She explains why science can continue to track the development of the corona situation.
SRF News: What is the point of the federal corona updates if far less is tested?
Tanja Stadler: Since January 1, 2023, a test has only been paid for if it has a medical benefit. Of course, we have fewer positive cases because of this. The aim of the tests is no longer to monitor the pandemic, but to generate an individual, medical benefit. The point is that if a person tests positive, they receive special medical treatment.
How well informed is Switzerland then about the current infection situation?
In the meantime, other types of surveillance have been set up or expanded in Switzerland. In this regard, wastewater monitoring has become very important. Wastewater samples are taken several times a week at various locations in Switzerland.
The concentration of Sars-CoV-2 – but also other viruses – in the wastewater is recorded. If this increases or decreases, we can conclude that the incidence of infection is also increasing or decreasing. Already in autumn 2022 a lot less was tested. And even then, wastewater monitoring was a very important method for recording the infection process.
In parallel, we have the Sentinella reporting system. There, symptomatic patients are tested in selected household practices; This shows whether Sars-CoV-2 is spreading more or less.
Are these surveillance systems sufficient to know about the pandemic situation in Switzerland?
These two methods allow us to get a relatively good idea of whether the number of infections is going up or down. We recognize whether an epidemiological wave is spreading or receding. Of course, the absolute number of infections cannot be determined with this.
Is it dangerous if the number of unreported cases is higher and we don’t know exactly what the infection situation is?
On the one hand, it has to be said that we never knew exactly how high the number of unreported cases was during the entire pandemic. We never tested all people who were potentially infected. If you want to accurately record the number of unreported cases, you would have to test a selected group of the population again and again. Then you would see how many people are positive.
In terms of health policy, the question arises as to whether it is even necessary to know how high the number of unreported cases is. For most interventions in recent years, it was enough to know how the dynamics are developing: does the data indicate that things are going up or down? At the same time, it is important to know which variants are circulating: is there a risk that a new, potentially more dangerous variant will emerge?
The conversation was conducted by Nicolas Malzacher.