What do we know about this topic that we don't yet know? Where could statistics potentially support in the future?
In general, of course, these are things like the effectiveness of vaccination, whether one is immune after surviving an infection, etc. But also smaller ambiguities, such as whether there are differences in mortality between the sexes, etc. Here we just have to wait until there is more data available.
We know very little about what contact patterns look like, how and when they change, and what all the reasons for that might be. In the first wave, the measures worked so well in this country partly because there was a relatively high level of fear, following the fresh images from Italy. However, things like fear cannot be measured properly, which is why it is always difficult to predict the exact effect of a measure.
We also don't know how exactly average testing behavior can change. There were very few tests over Christmas and New Year's Eve, for a variety of reasons. Without precise knowledge of these causes and their effects, however, it is difficult to make any meaningful extrapolation from the available data as to how many infections there really were.