The case fatality rate (CFR), the number of people who have died from the Covid-19 over the number of people whose infection has been confirmed, has been falling for months. The demographics of the infected patients has been changing, too.
The percentage of infected people over 65 is now close to a third of what it was in late April. Could that explain most of the CFR decrease? I ran a test, assuming the following CFR’s:
- 0-17 — 0.05%
- 18-49 — 2%
- 50-64 — 4%
- 65 and older — 17%
The results:
I didn’t try to optimize the fit by manipulating the CFRs for each cohort, but this is by no means definitive. On the other hand, it is suggestive. OF course, there have been other changes that could affect the CFR:
- Improved treatment
- Undercounting of cases varying as a function of time
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