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Coronavirus: The Scary Numbers

I published an article yesterday in which I estimated that the total number of people who will have died from Covid-19 by April 26, 2020, could be as high as 213,504. A friend pointed out to me that there was another, potentially more accurate way of predicting deaths.

Yesterday, I estimated the true number of people who were, or had been, infected with the SARS-CoV-2 virus in the USA on March 29, 2020, not just the confirmed cases, by dividing the total number confirmed deaths on March 29 (1,668) by an updated and more realistic mortality rate (0.5%). Then the expected total number of deaths, not accounting for interventions, 28 days later (by April 26, 2020) could be estimated by multiplying that number by 2⁷ (=128) to account for seven doublings over the seven four day periods. This produced the estimate of 213,504 (= 1,668 / 0.005 * 128 *0.005). Note that the mortality rate cancels out, and all that matters is the rate of doubling, which was every four days before the shelter-in-place orders.

An alternative approach is to start with the number of confirmed new deaths on March 29: 425. Divide that by the mortality rate to get the number of new infections roughly sixteen days (incubation + course of illness) before: 425 / 0.005 = 85,000. Then double that four times (2⁴ = 16) to estimate the number of new infections on March 29: 1,360,000. Then wind it forward by 12 days (multiply by 3 doublings = 2³ = 8) to get the number of new infections 16 days before April 26: 108,800,000. Finally, multiply that number by the fatality to rate to get an estimate of the number of new deaths on April 26: 544,000.

So, assuming our actions to slow the spread have not managed to increase the number of days per doubling beyond four days, then a reasonable estimate of the number of new confirmed deaths (in a single day) in the US on April 26 is 544,000. That’s a way more scary estimate than 213,504 total deaths.

This estimate assumes that the attempts to slow the spread are ineffective and that the recent true mortality rate has been 0.5%; that could actually be lower, or it could be as high at 1%. The estimate also assumes that the mortality rate will not increase due to our medical infrastructure being totally overwhelmed.

If the true current mortality rate is actually 0.2% (as I’ve heard suggested) but increases to 1.5% going forward as the medical system is overwhelmed, while the doubling rate is slowed from four to six days, then the number of new deaths on April 26 will be: 204,000 (425 / 0.002 * 16 * 4 * 0.015). Let’s let that sink in: 204,000 deaths (in the US) in a single day.

So the number of deaths on April 26 may be in the range 200,000 to 550,000.

As someone else pointed out, this does not account for the number of deaths caused by there not being medical facilities to take care of other non-Covid-19-related emergencies. But to put this estimate in perspective, as it stands, according to ASIRT, the average number of people who die each day in the US in road traffic accidents is 101.

So stay home, wash your hands, and don’t touch your face. Visit cdc.gov for the latest info.

Written by

An engineer-psychologist focused on machine intelligence. I write from my own experience to support others in living more fulfilling lives | duncanriach.com

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