Instead of 6, almost 100 sewage treatment plants are now looking for traces of corona, and the stool of 70 percent of the population is to be recorded in this way. However, there is still no nationwide monitoring of reinfections, immunity levels or long Covid.
After more than two years of pandemic, we are in the midst of a new wave of infections. Thanks to BA.5, case numbers are increasing and test positivity is skyrocketing. Around every second test is currently positive, which means far too few tests are being carried out to get an appropriate picture of the infection situation.
It is precisely in this situation that the Federal Office of Public Health (BAG) provides new figures on an innovative method of virus surveillance: wastewater monitoring. Because humans excrete traces of the virus RNA, they are detectable in wastewater. The collection and evaluation of this data has now been expanded.
So far the project was limited to 6 sewage treatment plants. Around 70 percent of the population is now to be recorded using data from 103 sewage treatment plants. The data has been collected since February and has been published since July. They are currently available for 99 sewage treatment plants.
The advantage of the wastewater analysis: Even those who don’t get tested go to the toilet. There are traces of the virus in the stool, which can later be detected in waste water samples. Thanks to the large number of measured values, the viral load in Swiss wastewater can now be determined relatively reliably. The falling number curve is very similar to that of the sewage traces.
New virus variants should also be recognized more quickly thanks to the large coverage. According to the BAG, systems in tourist regions were also explicitly selected in order to be able to detect any introduction in this way at an early stage.
No early warning system
But wastewater measurement is not a panacea in the fight against the virus. Just because the process takes time. “Because the processing of the wastewater samples can take up to a week, the wastewater monitoring is not an early warning system,” says BAG spokeswoman Simone Buchmann.
A look at the data also reveals that many of the sewage treatment plants deliver the samples with a delay of a few days or even weeks. The data for the last few days are therefore less reliable. For this reason, they are not shown in the graphic above. In addition, the office also only publishes the corona data weekly. A more or less complete picture only emerges with some delay.
The number of sequencings has also fallen sharply since April, and fewer virus samples are being examined for new variants. At the time of going to press, the FOPH was unable to answer why sequencing is no longer being carried out when the number of cases is increasing, whether this will soon be the case due to the new wastewater data and whether the process of wastewater analysis will be accelerated.
Switzerland-wide studies are lacking
In addition to the number of cases and new variants, other questions are crucial for the next few months: How well does the vaccination last, how well does the booster dose? How many people have antibodies, how many people have been infected more than once? How many people are affected by Long Covid, who is most likely to be affected?
There are studies from Switzerland on all these questions. In the canton of Vaud, for example, postal workers, asylum seekers or retail employees were examined to see how many people had already built up antibodies. In Zurich, it was determined that around a quarter of the study participants who contracted the original type in 2020 were not fully fit again after six to eight weeks. In the meantime, however, these results are already outdated thanks to new variants.
The Corona Immunitas study examined the degree of immunity in the Swiss population until March 2022. Since then there have only been isolated regional studies. It’s different in the UK, for example: Here, there are regular events for all parts of the country and across all age groups raisedwho has what levels of antibodies in their blood. The number of cases also includes whether it is a first infection or a reinfection.
Long Covid reporting office “not proportionate”
Such an expansion of the immunity studies is not planned in Switzerland: “Because the regional differences due to vaccination and natural infections are becoming smaller and smaller, it is not necessary to continue to carry out the surveys in all 14 study centers,” write those responsible Corona Immunitas on their website.
Also a national long-Covid register, like this required by the Altea network was not planned. The BAG says that various ways of recording long-Covid cases have been examined. “It has been shown that a complete record or exact count will not be possible due to the diverse clinical pictures and the changing symptoms over time,” says BAG spokeswoman Simone Buchmann.
In order to be able to set up a national long-Covid register, Parliament would first have to create the necessary legal basis. “However, the BAG does not consider such a register to be proportionate due to cost-effort-benefit considerations,” says Buchmann. Nevertheless, the data evaluation will be expanded in the future in order to be able to observe dynamics in new variants.