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COVID analytical update for Wednesday, May 20

Today we see near record test reports and a near record high negative test ratio. That’s good.

I’ve added NJ to the mix of states I’m analyzing, and changed the presentation a bit to compare some states on the same graph. I think this helps understand the relative impact of COVID on neighboring states. So far, I’ve combined NJ and NY, and NC and VA.

Much has been made in the press of the Case Fatality Rate (or CFR). It is widely reported at about 6%. This is not an entirely useless statistic, but should not be confused with the mortality rate. The CFR is simply the number of reported deaths divided by the number of reported cases. To calculate a mortality rate (the probability of dying IF you have contracted COVID) it is necessary to model how many people have the disease at any one point in time (many more than the reported cases), and then determine the number of deaths emanating from that cohort. I did this last month, and calculated an overall mortality rate of about 0.5%, but much higher for senior citizens and near zero for younger people (see below). Just to satisfy my curiosity, tomorrow I’m going to calculate the Case Fatality Rate for the seasonal flu. I suspect it’s higher than that for COVID, but neither should be used as a proxy for the probability of death – standby…

I’m also working on a calculation for the mortality rate for those under 65 without existing morbidities. This will be an important number, as it will represent the probability of dying from COVID for the healthy population under 65. It’s obviously a very, very low number, but I’m seeking to quantify it.

As always, feel free to send me your questions about my assumptions, methodology, or modeling in general.

  • Likely date of active case peak (Chalke modeling): April 10
  • Likely date of peak deaths (IHME): April 16 (last revision on May 18)
  • Short term projection for active cases tomorrow: 155,000
  • Total Test Results reported today: 413,794 (very high)
  • Total Pending tests reported today: 2,973 (very low)
  • National reported case Growth Rate today: 1.4% (very low)

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