Discussion
We conclude that the 4-week soft to moderate shutdown started on Nov 2
cannot on its own be expected to prevent a third, possibly even stronger
wave of COVID-19. Repeated shutdown periods (with moderate to severe
restrictions) could allow basic activities to be maintained, while
keeping the COVID-19 waves under control. Maintaining the measures
already partially introduced in October until spring of 2021 together
with some of the measures announced on Oct 28, and possibly combined
with short-term stronger restrictions, seem to promise the containment
of the epidemic in Germany through the winter. Come spring, shifting of
social activities to outdoors settings, possibly accompanied by
availability of save and effective vaccines, may help suppressing the
long winter outbreak.
We note that the observations above and simulations shown in Fig. 2 are
based on mathematical models that, as a matter of principle, only
describe a part of reality. In particular, reactions of the population
to increasing case numbers (more cautious behavior, self-limitation of
physical contacts) on the one hand and less than perfect compliance with
officially mandated restrictions on the other hand may lead to
significant deviations from theory. It is mathematically not possible,
based on reported cases, to quantify the effects of any single
intervention measure, as there have only been varying combinations of
measures in the short history of COVID-19 control. Possibly the
strongest limitation of mathematical modeling in the context of COVID-19
forecasts is that these are based on official case counts only, hence
solely on detected cases. The unknown detection ratio, which is most
likely fluctuating in dependence on new cases and testing capabilities,
might significantly affect the outcome of model simulations [9]. In
order to model the occupation rate of ICU beds, we assumed that the same
standard for admission to and release from intensive care is uniformly
applied over time. Changing this admission policy over time in reaction
to higher demand may lead to lower ICU occupation than shown in the
model. Finally, the presented model results cannot - and do not intend
to - make any statements about possible economic or social effects of
contact restrictions.