The measures taken at the beginning of November were designed to reduce the dynamics of infections and thus to bring the so-called reinfection rate R to a value below one. Judging by the current data, this has not been fully achieved.  Further restrictions have been in place since 16.12.  We do not believe that these further restrictions are restrictive enough in the literal sense to achieve a rapid drop in new infections; we are therefore again dependent on the population meeting significantly less privately than is still permitted under the rules.  

We recommend to take direct guidance from hospital admission figures; as long as these do not show a clear downward trend, the situation remains critical.  According to our information, cases requiring hospitalisation are admitted on average as early as four days after the onset of symptoms; the RKI case figures are currently often not available any faster and are also difficult to interpret due to the repeated need to adjust the testing strategy.

The planned vaccinations are helpful, but according to our simulations they do not bring about a rapid trend reversal either.  The situation will improve anyway towards summer due to the shift of outdoor recreational activities; according to our simulations, the vaccinations shift the time from when the epidemic is under control  forward by 2-3 weeks.  

As in previous reports, we discuss the different types of activities.  We consider it irresponsible to reopen schools without a mask requirement even in classrooms as well as alternate classes as long as hospital admissions do not trend significantly downwards.  According to our simulations, leisure activities continue to be particularly critical for infection dynamics; according to our simulations, a significant reduction of this component is achieved by a curfew, e.g. from 8 pm.

Our mathematical model is now capable of making approx. 2-week forecasts for all federal states.  What is still needed is a better identification of so-called change points, as otherwise the model reacts too slowly to changes in contact restrictions.
