100,000 to 240,000 COVID-19 Deaths in the U.S.?

REVISED ESTIMATES (INDICATED BY STRIKETHROUGHS) TO ADJUST FOR THE ADDITION OF DATA THROUGH APRIL 1, 2020, INCLUDING PREVIOUSLY MISSING DATA FOR THE STATE OF WASHINGTON.

Using some simple linear models of the rates of growth in U.S. coronavirus cases and deaths, I predicted that cases would top out at 250,000 and deaths wouldn’t exceed 10,000. I assumed that

lockdowns, quarantines, and social distancing continue for at least two more weeks, and assuming that there isn’t a second wave of COVID-19 because of early relaxation or re-infection.

I also said that, in any event,

the final numbers will be well below the totals for the swine-flu epidemic of 2009-10 (59 million and 12,000) but you won’t hear about it from the leftist media.

Is it time for me to back off my bold predictions, in light of the “official” estimate of 100,000 to 240,000 deaths that was announced at yesterday’s White House briefing? Probably.

First, let’s look at the numbers:

  • The Spanish flu pandemic of 1918-19 resulted in a maximum of 675,000 deaths out of 29 million U.S. cases — a fatality rate of 2.4 percent.
  • The H1N1 pandemic of 2009-10 resulted in 12,000 deaths out of 59 million U.S. cases — a fatality rate of 2/100 of one percent.
  • COVID-19 is (thus far) more lethal than the two earlier pandemics — 4.6 percent of the number of cases reached 5 days earlier. (A 5-day lag yields the strongest correlation between new cases and new deaths.)

Rounding up to 5 percent — and assuming that the rate remains constant — a total of 100,000 deaths means a total of 2 million cases, and a total of 240,000 deaths means a total of 4.8 million cases. As of today, the number of cases is somewhere above 200,000. Will the number of cases increase 10-fold to 24-fold, or more? Will the fatality rate rise?

Lacking detailed knowledge of how the official estimates are derived, I computed non-linear estimates of the rates at which new cases and new deaths will occur, based on statistics through March 31, 2020 (though numbers for Washington haven’t been posted for three days) April 1, 2020. The rate of increase in new cases declines gradually (the function is a decaying exponential) and never reaches zero, but approaches it by the end of June 2020. The rate at which new cases yield new deaths declines gradually, from a base of 5.8 6.6 percent, as the number of new cases increases (the relationship is a power function with an exponent of less than 1).

The bottom line: By July 1, 2020, the total number of cases in the U.S. will may reach 800,000 870,000, resulting in 35,000 40,000 deaths. That’s a fatality rate of about 4.3 4.6 percent per case and 1/100 12/1,000 of 1 percent of the country’s population.

Again, I assume that lockdowns, quarantines, and social distancing continue (though for how long I can’t say). I also assume that there won’t be a second wave of COVID-19 because of re-infections or an early relaxation of precautions.

Why is my revised and more sophisticated estimate of the number of deaths so much lower than the official one? It’s probably true that the official estimate simulates the spread of the contagion, whereas my general model doesn’t do that. But my guess is that the official estimate has been inflated to scare people into staying at home, which will reduce the rate at which new cases arise and prevent the number of deaths from reaching 100,000 or more.

COVID-19 in the United States

I have created several charts based on official (State-by-State) statistics on COVID-19 cases in the U.S. that are reported here. The statistics exclude cases and deaths occurring among repatriated persons (i.e., Americans returned from other countries or cruise ships).

The source tables include the U.S. territories of Guam, the Northern Mariana Islands, Puerto Rico, and the Virgin Islands, but I have excluded them from my analysis. I would also exclude Alaska and Hawaii, given their distance from the coterminous U.S., but it would be cumbersome to do so. Further, both States have low numbers of cases and (as yet) only 3 deaths (in Alaska), so leaving them in has almost no effect on the results displayed below.

All of the following charts are current through March 30, 2020. Based on statistical relationships underlying the charts, I stand by the prediction that I made on March 29, 2020:

Assuming that lockdowns, quarantines, and social distancing continue for at least two more weeks, and assuming that there isn’t a second wave of COVID-19 because of early relaxation or re-infection:

  • The total number of COVID-19 cases in the U.S. won’t exceed 250,000.
  • The total number of U.S. deaths attributed to COVID-19 won’t exceed 10,000.

In any event, the final numbers will be well below the totals for the swine-flu epidemic of 2009-10 (59 million and 12,000) but you won’t hear about it from the leftist media.

UPDATE 03/31/20: Some sources are reporting higher numbers of U.S. cases and deaths than the source that I am using for my analysis and predictions. It is therefore possible that the final numbers (according to some sources) will be higher than my predictions. But I will be in the ballpark.

UPDATE 04/01/20: See my revised estimate.

*   *   *

As indicated by Figure 1, the number of cases is about 1/20th of 1 percent of the population of the U.S.; the number of deaths, about 1/1,000th of 1 percent. Only 1.8 percent of cases have thus far resulted in deaths. Note the logarithmic scale on the vertical axis. Every major division (e.g., 0.01%) is 10 times the preceding major division (e.g., 0.001%).

Figure 1

I have seen some comparisons of the U.S. with other countries, but they use raw numbers of cases and deaths rather than cases and deaths per unit of population. The comparisons therefore make the situation in the U.S. look far worse than it really is.

Nor do the publishers of such comparisons address cross-country differences the completeness of data-collection or standards for identifying cases and deaths as resulting from COVID-19.

In any event, Figure 2 shows how the coronavirus outbreak compares with earlier pandemics when the numbers for those pandemics are adjusted upward to account for population growth since their occurrence. (Again, note that the vertical axis is logarithmic.) The number of COVID-19 cases is thus far only about 2 percent of the number of swine-flu cases; the number of COVID-19 deaths is thus far about 16 percent of the number of swine-flu deaths. So far, COVID-19 seems to kill a higher fraction of those infected than did the swine flu, but on present trends (discussed below) it may not prove to be any more lethal than the swine flu.

Figure 2

As shown in Figure 3, the daily percentage change in new cases is declining, as is the daily percentage change in new deaths.

Figure 3

However, new deaths necessarily lag new cases. As of yesterday, the best fit between new cases and new deaths is a 5-day lag (Figure 4). At the present rate, every 1,000 new cases will yield about 34 new deaths. This ratio has been declining daily, which is another bit of good news.

Figure 4

Figure 5 shows the tighter relationship between new cases and new deaths (especially in the past two weeks) when Figure 3 is adjusted to introduce the 5-day lag.

Figure 5

Figure 6 shows the similarly tight relationship that results from the removal of the 6 “hot spots” — Connecticut, the District of Columbia, Louisiana, Massachusetts, New Jersey, and New York — which have the highest incidence of cases per capita.

Figure 6

The good news here is the the declining rate of increase in the incidence of new cases, both nationwide (including the “hot spots”) and in the States that have been less hard-hit by COVID-19. The rest of the good news is that if the rate of new cases continues to decline, so will the rate of new deaths (though with a lag). Thus the prediction at the top of this post.

COVID-19 Update and Prediction

I have updated my statistical analysis here. Note especially the continued decline in the daily rate of new cases and the low rate of new deaths per new case.

Now for the prediction. Assuming that lockdowns, quarantines, and social distancing continue for at least two more weeks, and assuming that there isn’t a second wave of COVID-19 because of early relaxation or re-infection:

  • The total number of COVID-19 cases in the U.S. won’t exceed 250,000.
  • The total number of U.S. deaths attributed to COVID-19 won’t exceed 10,000.

In any event, the final numbers will be well below the totals for the swine-flu epidemic of 2009-10 (59 million and 12,000) but you won’t hear about it from the leftist media.

UPDATE 03/31/20: Some sources are reporting higher numbers of U.S. cases and deaths than the source that I am using for my analysis and predictions. It is therefore possible that the final numbers (according to some sources) will be higher than my predictions. But I will be in the ballpark.

UPDATE 04/10/20: See my revised estimate.