I get why this keeps getting compared to the seasonal flu. It's something we are all familiar with. But part of that is what makes this a bad comparison in my opinion. Vaccination is wide spread, I imagine there is some lingering immunity among the population, and we know how to handle it because we are familiar with it. Would not a better comparison be to the 2009 H1N1 flue strain? it was novel so there was 0 existing immunity or vaccination in the population, and had a similar transmission mechanism. To me this should be a case study in spread rates and extents if we did not implement adequate controls. estimates are that 11%-21% of the global population got it. (700MM-1.4B) and 61MM in the US. final estimates were an R0 of 1.46 so if the current estimates of the COVID-19 R0 in the 1.5-3 range are accurate we could expect at least those numbers of infected assuming minimal intervention.
Where the problem comes is even if you use the high side of the death estimate and low side of the infected estimate, the CFR for 2009 h1n1 was only 0.08%. Looking at all of the data, the lowest CFR for any country with a significant number of cases is currently sitting at about .25%. So best case scenario we are looking at a virus that is equally as contagious, and 3 times as deadly as the swine flu pandemic. that's nearly 2MM global deaths and up up to 150k in the US. Looking at the top 15 countries by case count though, the CFR numbers look like they will wind up being worse. the aggregate CFR is 4.2%, average by equally weighting each country is 2.43%, and taking out the top and bottom outliers looks to settle in the range of 0.8% to 3.5%.
The diamond princess cruise is a great microcosm case study due to the high level of testing vs population. here they wound up with 696 cases and so far 7 deaths, with 15 remaining cases in serious/critical condition. here we think we have a good handle on the total case count so the CFR should be pretty accurate. If no new deaths happen the CFR is 1%, if all 15 remaining serious cases die that puts it at 3.16%. This data, at least to me, makes the global numbers of 0.8% to 3.5% seem to be narrowing in on the correct range for this virus. With that in mind, that would put the range of global deaths at 5.5MM-42MM using low-low, and high-high (infections-CFR) numbers to set the range, with the more likely range being in the 7MM to 20MM. Or just looking at the US that would put us in the range of 500k to 1.8MM deaths.
I personally think these numbers are good to look at because they seem pretty indicative of the impact should we do nothing or implement minimal precautions like with swine flu. It also makes it pretty clear why many in leadership have deemed major societal response as being necessary. Hopefully we see nothing close to those numbers, but looking at 2009 h1n1 numbers, that would mean to me that our drastic response was effective.
I am no expert in medicine, just an engineer looking at the numbers and trying to make sense of it all, so take my ramblings for what they are worth, hopefully at least slightly more than you paid for them.
