Matthias Schrappe, Hedwig François-Kettner, Matthias Gruhl, Dieter Hart, Franz Knieps, Philip Manow, Holger Pfaff, Klaus Püschel, Gerd Glaeske: Thesenpapier 6. Teil 6.1: Epidemiologie. Die Pandemie durch SARS-CoV-2/CoViD-19. Zur Notwendigkeit eines Strategiewechsels (Thesis Paper 6. Part 6.1: Epidemiology. The pandemic caused by SARS-CoV-2/CoViD-19. On the necessity of a change of strategy), Thesenpapier Version 6.10 Köln, Berlin, Bremen, Hamburg November 22, 2020.
The most important messages at a glance
1. Unreported number significantly larger than known reporting rate: Simple model calculations show that the “unreported number” of infections in the untested population is many times higher than the number of known, newly reported infections (reporting rate). If the prevalence of 1% from the total population coverage of Slovakia is taken as a basis, the number of known reports of infections in the non-tested population in one week in Germany is 815,000, compared to 130,000 known reports in the non-tested population. Consequently, the guideline and limit values, which are based solely on the reports of infections after testing, cannot be given any significant significance as they cannot be reliably determined.
2. Seroprevalence studies (antibodies) show unreported numbers between factor 2 and 6: The present seroprevalence studies were conducted very early in the epidemic, mostly in direct connection with the so-called 1st wave. The cumulative perspective of the antibody determinations indicates an estimated number of unreported cases between factor 2 and factor 6 compared to the cumulative findings from PCR diagnostics. From Madrid first data have been published, which are above 50% and could mean a partial immunization of the population.
3. The currently used limit values give a false picture and cannot be used for control purposes and political decisions: According to the findings of modern organizational theory and system control, key figures and limit values used for control purposes must be reliable, valid, transparently developed and understandable, and must be implementable (achievable) for those affected. The currently used limit values, which were also included in the amendment of the Infection Protection Act (e.g. “35 cases/100,000 inhabitants”), primarily lack reliability of measurement, as they cannot be distinguished from the estimated number of unreported cases (see above). However, unreliable limit values can also be invalid, i.e. they cannot be applied meaningfully because they do not measure what they are supposed to measure. Furthermore, the targets (“we have to get below 50/100,000 again”) are unrealistic and therefore violate the central precept of achievability.
4. Two new control instruments are proposed which, in view of the lack of cohort studies, cannot do without the reporting rate, but which make this error-prone value more meaningful through other parameters. The newly developed notification index NI describes the dynamics of development at the national or regional level. It relates the notification rate (M “x cases/100,000 inhabitants”) and the rate of positive test results (T+) to the test frequency (Tn) and to a simple heterogeneity marker (H), and allows the bias to be balanced, e.g. by test availability or by the occurrence of a single large cluster. The second index (hospitalization index HI) describes the burden on the health care system in a region and is calculated as the product of NI and the hospitalization rate.
5. The most important outcome parameters show a positive development: the hospitalization rate is decreasing or stabilizing despite the increasing age of the infected persons, the respiratory rate has been decreasing since the beginning of the epidemic, and in particular mortality is decreasing, both among intensive care patients and in the collectives of employees in hospitals, nursing homes and care facilities. It certainly makes sense to highlight positive developments as part of a reorientation of the overall strategy towards a more comprehensive protection concept.
6. Problematic findings on intensive care capacity: there has been a significant increase in the number of intensive care patients with CoViD-19 and thus also a decrease in the free intensive care capacity. However, an absolute decrease in the total intensive care capacity in Germany can be observed in parallel, which has a large share in the decrease of free intensive care beds. With the available data this effect cannot be explained, an analysis on political level seems necessary.
7. Cohort studies are still urgently needed: In order to solve the problems described in all the thesis papers published to date by sample selection, prospective cohort studies are necessary and must be initiated even today. They must comprise randomly selected population samples that are regularly (e.g. every 14 days) examined for the recurrence of an infection with SARS-CoV-2/CoViD-19 (longitudinal design, PCR and/or antigen tests). It is important to note that cross-sectional studies on seroprevalence (antibodies) are not considered cohort studies because they are retrospective (detection of past infections). Cohort studies allow central statements to be made on the development of frequency, infection pathways, symptoms and risk groups. Furthermore, cohort studies are essential for planning and evaluating vaccination campaigns.