  This is work in progress. We make it accessible hoping that people might find
the idea useful. We propose a discrete, recursive 5-compartment model for the
spread of epidemics, which we call {\em SEPIR-model}. Under mild assumptions
which typically are fulfilled for the Covid-19 pandemic it can be used to
reproduce the development of an epidemic from a small number of parameters
closely related to the data. We demonstrate this at the development in Germany
and Switzerland. It also allows model predictions assuming nearly constant
reproduction numbers. Thus it might be a useful tool for shedding light on
which interventions might be most effective in the future. In future work we
will discuss other aspects of the model and more countries.
