Since the last report, we have dealt in detail with the modelling consequences of aerosols as a propagation mechanism of SARS-2. We summarize our current state of understanding in "rough rules", with which the effects of measures can be roughly calculated in a sort of modular system.

With regard to schools we continue to conclude, as in previous reports, that infections in schools do not have a particularly large direct influence on the overall infection dynamics. Masks, frequent ventilation and, if necessary, (significantly) reduced numbers of participants would reduce the remaining infections to a quantity that is irrelevant to the overall dynamics.

A clear driver of infection incidence is the leisure sector. In particular, after the seasonal shift of activities into indoor areas, we expect three categories of activities of roughly equal relevance: "going out (restaurants/cafes/etc.)", "family celebrations" and "private visits". According to our current model calculations, each of these categories generates approximately as many infections as the contribution of educational institutions to the overall infection dynamics. A reduction of infections in these areas seems difficult, but must be successful in order not to overtax the system of contact tracing.
