As temperatures drop, respiratory diseases are on the rise. But Covid-19 of all things - unlike in previous years - has been on the decline for weeks. The hospitals are also emptying. Epidemiologist Ulrichs names ntv.de a possible cause.
Even after almost three years of the pandemic, the corona virus continues to be unpredictable: the severe winter wave expected by many has not yet become apparent. On the contrary, the number of infections recorded in Germany has been falling for weeks. And there are also fewer patients in the Covid 19 intensive care units. At the same time, according to the Robert Koch Institute (RKI), other respiratory diseases such as flu are increasing - depending on the season. Only with Covid-19 is it different, and that is very different from previous years.
This also amazes the epidemiologist Timo Ulrichs from the Akkon University of Human Sciences: "In fact, I did not expect this development. I had assumed a larger autumn and winter wave," says Ulrichs to ntv.de. But what is the reason for the decline in the key figures? "It is possible that there is now a certain herd immunity in the population through vaccinations and surviving infections," explains Ulrichs in an interview.
The nationwide seven-day incidence has been declining for weeks and, according to the RKI, had recently reached its lowest level of the year at around 180. However, experts have been assuming for some time that there will be a large number of cases not recorded by the RKI - mainly because by far not all infected people have a PCR test done. Only positive PCR tests count in the statistics.
Of course, it is possible that many cases are not recorded due to a change in testing behavior, says epidemiologist Ulrichs. However, the also declining number of Covid intensive care cases in hospitals suggests that the trend is actually declining. And there is no sign of a trend reversal towards a winter wave, says the expert. For example, the wastewater surveillance that has now been established in Germany does not provide any indications of this.
During wastewater surveillance, wastewater samples are now being examined for traces of Sars-CoV-2 at up to 25 locations across Germany. Gene fragments of the virus get into the sewage through the excretion of urine, feces and saliva. Researchers hope to be able to use these wastewater analyzes to detect waves of infection earlier. According to the RKI, there have been more locations with falling trends than with rising trends since mid-October, as stated in the latest Corona weekly report. However, Ulrichs emphasizes that the number of corona indicators that will rise again in the future cannot be ruled out.
In addition, it is conceivable that a new corona variant will be better able to escape the existing immunity in the population - and then more people will become infected and fall ill again, predicts Ulrichs. However, this new variant would have to be "completely different" from the currently dominant omicron variant BA.5 and its sublines such as BQ.1.1. "But I think the likelihood of a completely new variant appearing is low. There is currently no evidence of this anywhere in the world."
Nevertheless, it is important that the existing measures against corona are maintained, emphasizes the epidemiologist. Wearing a mask and keeping your distance protected against infection and prevented the spread of the virus. "Vaccination with adapted vaccines against the omicron variants currently in circulation is also important for patients at risk," says Ulrichs.
