How Certain Are We that Excess Fatalities Are Declining

When each Week, Peak Excess Deaths Gets Pushed Further Out

Figure 1: Excess fatalities, 9/30 vintage (purple), 9/23 vintage (blue), 9/16 vintage (tan), 9/9 vintage (green), 9/2 vintage (red), 8/25 vintage (brown). Note excess fatalities differ from CDC series which are bounded below at zero. Source: CDC , various vintages, and author’s calculations.

 

Figure 2: Covid-19 fatalities, 9/30 vintage (purple), 9/23 vintage (blue), 9/16 vintage (tan), 9/9 vintage (green), 9/2 vintage (red), 8/25 vintage (brown). Source: CDC , various vintages, and author’s calculations.

In fact, both of the CDC series – Covid-19 Fatalities and Excess Fatalities – drop off dramatically in recent weeks. If you didn’t read the notes attached to the CDC spreadsheet, you’d conclude that we’ve won! But inspection of the spreadsheet reveals notes that indicate that the most recent data is incomplete. In fact, as I show in this post, about the four most recent weeks worth of data are going to be substantially revised. I shade this period in green in the above graph. A hint that this is a substantial problem is provided by comparing the trajectory of the unofficial tally compiled by the Our World in Data, which indicates a much smaller decline (figure 3).

The current vintage’s August 15th observations is moved up from the previous vintage so that excess fatalities are essentially flath through the 15th. CDC designated Covid-19 deaths for the week ending August 15 rose 145 going from previous to latest vintage; excess deaths rose 942 from the previous vintage to the current.

These observations are important to keep in mind when inspecting Figure 3.

Figure 3:  Weekly fatalities due to Covid-19 as reported to CDC for weeks ending on indicated dates (black), excess fatalities calculated as actual minus expected (teal), fatalities as tabulated by Our World in Data (dark red). Note excess fatalities differ from CDC excess fatalities series which are bounded below at zero. Light green shading denotes CDC data that are likely to be revised. Source: CDC  9/30/2020 vintage, OurWorldinData accessed 9/30/2020 and author’s calculations.

Hence, excess fatalities over the last month might or might not be falling.