What was recently read in “Bild” sounded like a liberation for many. With these words, the longed-for end of the corona measures no longer seemed distant: “Finally,” incidence should no longer be the measure of all things. This number of registered new infections per 100,000 inhabitants in Germany determines whether children are allowed to go to school and restaurants are allowed to serve guests, and most recently fell below 10. The federal emergency brake was rigidly linked to them. Has it come to an end now? The daily referred to an internal document from the Robert Koch Institute (RKI): The number of Covid patients who are in hospital is to be introduced as a further leading indicator.

The Ministry of Health immediately made it clear: This would not change the political strategy - the incidence was still an important parameter. When the government now broadens its view of the situation in the hospitals, it is accommodating the experts who have been calling for months to consider as many data points as possible when fighting a pandemic - and not to tie everything to one value. For many, that doesn't go far enough. Even after more than a year of a pandemic, it takes a lot of effort in this country to even record the patient numbers from the hospitals.

In order to assess how helpful certain data are, you first have to be clear about what goal you are actually pursuing. For example, if you want to minimize the risk of mutants of the coronavirus spreading, you have to keep the absolute number of infections low. As few people as possible should be infected. The incidence can help here, it provides information on the infection process - but the quality of the data also counts. One problem is that the health authorities report the number of infections to the RKI with a certain delay, especially on weekends. This leads to a systematic underestimation of the current 7-day incidence, says the German Statistics Working Group. In addition, there is an unreported number behind the incidence - infected people with weak symptoms or no symptoms at all,who cannot be tested fall through the cracks. How large the number of unreported cases is can only be answered by testing a representative sample of the population. There is such a project in England. This is what statisticians have been calling for in Germany for months. They are not answered.

The paradox of the corona measures

Another goal of fighting a pandemic is to protect hospitals from being overburdened.

This was the reason for most of the corona measures in Germany.

It is paradoxical: the measures depended on the incidence, which, however, is hardly suitable for this goal.

The number of new infections can point to possible trends in the population, but it is decoupled from the disease process.

There are two reasons.

First, the incidence depends on the testing strategy. When you test young people, like high school students, the incidence rises, but little changes in hospitals. This problem could be partially resolved by understanding the reason for the test. Scientists have also been demanding this in vain for months. An emergency solution would be to at least provide information on symptoms if the test result is positive. What will happen to the health system in the coming days can be estimated from the number of people infected with symptoms. But this is where the bureaucracy fails: Although the registration forms provide a field for information on symptoms, this information is missing for every fourth report to the RKI.

The second reason for the decoupling of incidence and disease is the vaccination campaign. The once highly endangered risk groups, i.e. people over 80 years of age or seriously ill, have now been largely vaccinated and thus protected from severe disease. Therefore, even with high incidences, they will not end up in hospitals as often as last year.