A while back, when it seemed like a lot of people were becoming ill with covid, I wondered how long it would take to get to herd immunity the hard way. It turned out that, although it seems like horrendous numbers are becoming ill, the percentages of the population were much smaller than I had intuited.
It’s time to do another calculation. IIRC, we didn’t have vaccines when I last did that calculation, and it was before Delta made its appearance. There’s not much talk about herd immunity these days because of Delta’s much higher transmissibility and maybe because it’s gotten mixed up in the “let it rip” crowd. I hope to write a post on R and those calculations one of these days.
I built a VERY simple Excel model. The point is to get a handle on the numbers, and two significant figures are good enough for that. If anything, it may overpredict deaths, which would be a change from our expectations of the last almost two years.
The state population numbers are from the World Population Review. The covid numbers are from last night’s New York Times tracking.
I converted the cases and deaths per 100,000 to percentages. I assumed that 10% of those vaccinated had been infected and removed that overlap. I also assumed that 10% of those vaccinated were still susceptible to serious cases of covid. I added the percent of cases to the adjusted 0.8 of vaccinated to get the immune %. The susceptible are thus everyone else. I multiplied the death percentage times the susceptible (this is probably the largest source of pessimism) to get the expected deaths.
The bottom line, expected deaths for the US, is close to 300,000, which will give a total close to a million dead from covid. That doesn’t count excess deaths from the overloading of the medical system. Combined immunities from illness and vaccination are not too different from the percent of vaccinations. The pandemic is far from over.
Photo: The Guardian
Cross-posted to Lawyers, Guns & Money
Nuclear Diner 
Thank you for doing these calculations! I read the spreadsheet and, sorry, it is unclear to me over what time frame is “The bottom line, expected deaths for the US, is close to 300,000, which will give a total close to a million dead from covid.”?
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That is for an overall total. When it is reached depends on how quickly people get vaccinated.
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I left a comment about this at LGM late last night. I think there is a simple error in the calculation of death percentage. Your numbers may be a lower bound.
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Welp, it’s hard to say much about this without more information.
And before you go into painful detail, I will say once again that this is an estimate, just something to get my brain around what to expect. It is not an attempt to nail down exact numbers.
In fact, my primary goal was to figure out how much people who recovered from covid contributed to overall immunity. The answer is not much.
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You are calculating the fraction of remaining susceptible people who will die, using the fatality rate so far. But you are using the fraction of total population that died, not fraction of infected. I’m not sure if that is painful detail, it seems like the very point of your calculation, and your fatality rates may be off by a factor of 3. I’m also not sure how this answers the immunity from COVID infection question. That is an assumption of your model. If you change that (say you get no immunity from previous infection) your numbers change by a lot.
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Seems to me that using the fraction of total (previously) susceptible population to calculate what will happen to the remaining susceptible population is reasonable. I’m not assuming everyone is infected.
Keep in mind that this is an estimate. There are a great many bells and whistles that I could have added to the assumptions, but my objective was to get a general feeling for where we are.
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