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.
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.
Update: After an afternoon offline, I quickly went through the comments when I came back. Some of you are spreading misinformation, or at least claiming more definite knowledge of SARS-CoV-2 biology than is justified. Be particularly careful of claims about waning immunity. From what I’ve read, we simply don’t know. The media magnify the uncertainty toward OMG WE WILL NEVER BE FREE OF THIS DANGER, but that is what they like to do. When you drill down to the data, it’s much more mixed, but I am not expert enough to work through the papers in detail. But, in the rough and ready style of this post, I’ll point out that we have less than a year of experience with the vaccines and the immune system has at least three layers of protection. So you may read my posts knowing I lean in the opposite direction from the media.
Photo: The Guardian
Cross-posted to Nuclear Diner