IHME Projects US Cases Are Actually Triple Those Measured at Now 7 Million

IHME Projects US Cases Are Actually Triple Those Measured.  US now at 7 million confirmed cases.  96,000 Lives Savable by Masking by January 1.

The Sept. 24 IHME projections are out, and are not much changed from last weeks.  However, we pursue further the actual number of Americans who have been infected, and make a crude and naive estimate of the number who may be infectious at the present time, and what that means to you.  Again, I am not an epidemiologist, so take these estimates with a grain of viral load.

First we start with the projections.  The number of US deaths recorded from the Coronavirus is currently 203,147.  The IHME projection for US deaths reached on January 1 is at 371,509, down slightly from a projected 378,000 last week, and 415,000 the week before.  Many of these occur in a holidays surge in the last weeks of December, based on what happened during the Southern Hemispheres winter.  This is due to in-person schools, cold weather forcing people indoors, the seasonal flu, and for us, students returning for the holidays and holiday celebrations.

The US is currently at only 48% masking.  The IHME estimate for 95% masking starting immediately would only result in an estimated total deaths of 275,062 by January 1, thus saving 96,447 American lives.  Since we are at at 203,147 current deaths, that would give 71,915 more deaths by January 1, instead of 168,362, with which to celebrate the New Year.  The almost 72,000 out of almost 170,000, which cuts down deaths to 43% of those without extra masking.  Comparison with other countries shows that even 80% masking gets rid of most of the extra deaths.  While masking reduces the risk of infection to the wearer to 1/3, social distancing reduces it to 1/10.  Outdoor cuts the rate down to 1/18 of that indoors.

Daily deaths on January 1 are currently projected at 3,052, but with 95% masking will be reduced to 1,185 deaths per day.  That is a reduction to 38.8% or about 40% to those with just current 48% masking.  Current deaths fluctuate around 1,000 per day.

Now we get into my naive use of the data.  The IHME estimated infections for Sept. 24 is 126,838.  Recent testing data of confirmed cases are around 40,000 per day for the US.  That means that the ratio of new cases to confirmed and counted ones is about 3.2 to 1.  Here is an even more naive assumption:  people who get infected, are infectious for 14 days.  They are actually maximally infective during their earliest days.  So if you have 40,000 x 3.2 = 127,000 new cases a day, times 14 days, gives 1.8 million infectious Americans on any given day.  With our 330 million population, that is one out of 180, or lets say, 1 out of 200 Americans is infectious on any given day.  When daily deaths triple by January 1, this will be 1 out of every 70 Americans.

Consequently, when you go to a political rally with say 5,000 unmasked, crowded, and yelling people, likely 25 infectious people will be there with you.  But wait, those surrounding you believe that the whole Coronavirus is a hoax, and have been acting in accord with that, exposing themselves every day without precautions, so the real number of infectious people could be many times that.

The state with the largest population (40 million) and almost tied with New York for projected Coronavirus deaths is California.  Currently we have 15,415 deaths from the Coronavirus.  The IHME January 1 projected deaths are 43,211, although this can be reduced to 28,073 by 95% masking, saving 15,133 lives.  That is almost as many as we have already lost!  Current masking in California is at 57%.  Without increased masking, we will lose 27,796 more, which can be reduced to 12,658 lives lost, a reduction to 45.5% of losses.

Now we stick our neck out again to note that on Sept. 24, there were an estimated 13,946 new infections, yet only about 4,000 are being confirmed a day in California.  That means that there are 3.5 times the number of actual cases as those confirmed.

Multiplying the 14,000 new infections a day times 14 days of infectiousness gives about 200,000 infectious Californians on any given day.  Out of 40 million Californians, that is 1/200 of the people you meet here are infectious.  This is the same number as for the US as a whole, and might in fact be built into the model.

We now estimate the fatality rate for the US from the model.  There are 200,000 US deaths out of 7 million confirmed cases giving an “apparent” rate of 2.9%.  Applying the US factor of 3.2 to give the real fatality rate gives 2.9%/3.2 = 0.90%, or slightly less than 1%.

We note that the IHME shows graphically the US detection rate at 23%, who’s reciprocal is 4.35, which would give the real fatality rate of 2.9%/4.35 = 0.67%.  We have used this in previous articles, but decided to try the other approach today.  Still, they are not that far apart, but we would of course prefer that the lower one be true.

Update:  Sept. 26.  Using the 4.35 factor of total cases over detected time 7 million detected cases give 30.4 million infected Americans.  Dividing by the US population of 330 million gives 9.22% of Americans infected.  Serology tests reported yesterday gave near 9% positivity or infection rate for the US, in good agreement with the IHME figures.

So what IHME essentially does is triple the probability of infection, but cut the fatality rate down to a third of the apparent rate.

About Dennis SILVERMAN

I am a retired Professor of Physics and Astronomy at U C Irvine. For a decade I have been active in learning about energy and the environment, and in lecturing and attending classes at the Osher Lifelong Learning Institute (OLLI) at UC Irvine.
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