Covid WI status update: Dec 30

Cases continue declining in Wisconsin. Deaths numbers plateaued for a while and are a bit erratic, but I expect them to decline overall in the future. As happened with Thanksgiving, I predict a relatively small, temporary spurt of new cases from the Christmas and New Year’s holidays.

Cases and deaths

Several weeks ago I predicted that deaths had peaked. The intervening weeks have proven this wrong. Here is an update of the graph overlapping Wisconsin’s reported case and death curves, with about a two week delay.

Clearly the death curve did not follow the case curve on its downswing, but instead stayed on an erratic plateau for a while. I think this is due not to anything strange with the virus, however, but to increased delays in recording deaths. The DHS website does provide data by date of death, in addition to the date of reporting. If I compare these curves, it is evident that the reporting delay increased during the fall surge. This is probably not surprising - health departments have had a lot more deaths to process.

Be wary in interpreting this date-of-death curve, because dates from up to 8 weeks ago are not complete yet. Another way of looking at the reporting delay, actually, is to compare the date-of-death curve today with the curve from a week ago. The difference shows when the deaths reported in the last week actually occurred.

Note that for this plot I’ve switched from 7-day averages to daily numbers. It shows that many of the last week’s reported deaths are from recent days, but that a substantial number are still coming in from mid-November.

I still think reported deaths should start trending downward soon, but for now the timing is going to depend more on reporting than on the previous weeks’ cases.

The lump of covid in our stocking

I believe careful analysis shows that Thanksgiving did cause a small, temporary spurt of cases. I would expect the Christmas holidays to have a similar, somewhat larger effect.

The reason I am more concerned now than at Thanksgiving is just that the Christmas season is a longer period of time, with New Year’s following closely. It is also preceded by more shopping and activity. Furthermore, since Thanksgiving did not create a large increase in virus, and we are further from Wisconsin’s peak, people may have decided to be less cautious for Christmas. The Google mobility data, indeed, show a much larger increase in visits to retail and recreation locations prior to Christmas than they did prior to Thanksgiving.

On the other hand, I would not expect people’s level of caution to change drastically, and it is true that we are at a lower level of virus activity right now. So my prediction would be that Christmas will cause a larger percentage increase of cases than Thanksgiving, but that the absolute case rate will not exceed the post-Thanksgiving mini-peak and the effect will still be temporary.

Here’s wishing for a happier 2021.