Sequential data assimilation of the stochastic SEIR epidemic model for regional COVID-19 dynamics

Ralf Engbert; Maximilian M. Rabe; Reinhold Kliegl; Sebastian Reich

The Robert Koch Institute (RKI), the central scientific institution in the field of biomedicine within the portfolio of the Federal Ministry of Health, provides daily access to the number of confirmed cases, deaths, and recovered patients, broken down by 412 counties, six age groups, and sex. As they are official records, only cases certified by doctors or labs according to a strict medical protocol in accordance with the Infection Protection Act are entered into the data base. The exact time of an infection is usually not known. The associated time stamp refers to the date on which the local health authority became aware of the case and recorded it electronically. As records are passed from the physician or lab via local and state health authorities to the RKI, there is a delay of several days before cases are available on the website. Statistics relating to the most recent three or four days are incomplete and cannot be interpreted; retrospective updates and corrections are possible for all days of the pandemic spell as they become available. Also the date at which the case is reported at the RKI (i.e., the Meldedatum) is not more recent than the date at which the infection occurred. We use data inclusive April 4, as reported on April 8, 2020; they are included as part of the supplement.