[The FeverApp Registry - A Way to Empower Parents through their Own Documentation to a Graduated Decision]

To demonstrate the feasibility and exemplarity of an app-based parent registry.

The app as an elaborated interactive electronic case report form and the underlying data structure of the registry are presented. The initial recruitment efforts are illustrated and the temperature distribution, as well as the distribution of fever events in 2020, are analyzed.

The FeverApp successfully collects data into a central registry. Like every study, it also provides information on the current knowledge. The ecological momentary assessment can represent the illness situation at several levels (measurement, fever episode, individual, family, practice, country). Methods for data collection needed to be developed in a flexible manner due to pandemic conditions. The initial recruitment goal of 2400 fever phases in the first two years was met, with nationwide dissemination pending. It is shown that body temperature does not rise indefinitely; fevers reach an average of 39 degrees without antipyretics, although in rare cases temperatures beyond 41 degrees are reached without harm. Furthermore, a comparison with a reference practice shows that fever episodes can be recorded more comprehensively in the app, including infections that do not come to the presentation in a pediatrician's office. Thus, the FeverApp fulfills in a model-like fashion the use of registers in persons basically healthy and maps a multi-level diagnostics.

The FeverApp could basically establish itself as a supporting tool, the registry can reliably collect data with the method used and maps the current infection situation. In researching the question of how infections develop in the post-Covid period, the app could perform an important task.