Fixed a typo. Here’s an updated version.
Good write-up but I disagree with it,
You are seriously underestimating both the health and economic costs of trying to get to natural herd immunity.
Let's use the low end estimate of 62%, (which is likely underestimating how many would need it).
62% of the 328M Americans is over 200,000,000 Americans would have to be infected (you would need children to get infected even though they tend to have mild symptoms)
If you could actually isolate all Americans over 60 and all Americans who would be at high risk that would be over 100M Americans. So the first place this idea falls apart is who is going to take care of 100M isolated Americans? Because anybody that interacted with them would have to be proven not have any COVID19 antibodies in their body to be safe.
Even if you could isolate those individuals and then used 50% of the current estimated death rates for the remaining age ranges from 19-60 that would create a best case scenario of 440K deaths. A moderate level scenario would mean 880K deaths. That is not sicknesses, that is deaths. The hospitalizations for that population would be in the tens of millions.
The economic devastation of this is also seriously understated. As people start getting sick and dying you lose both economic productivity and purchasing.
during the herd immunity phase over 130M Americans would have to miss at least 2 weeks of work, some would die and 10's of millions would get sick enough that they would require more than 2 weeks away. Many would be overloading our health care systems - while 65+ are over 75% of our COVID19 deaths, they are less than 45% of our hospitalizations. Even a decent percentage of young people require hospitalizations (currently a little over 15% of hospitalizations are 18-44), and the 45-64 age even with lower death rates than the 65+ crowd have high hospitalizations rates.
As we are already seeing in processing plants in states all over the US, all it takes is one person and all of a sudden you have hundreds of employees out and you either have to stop or severly curtail production. This also fails to take into account that by isolating all these individuals you are removing a not insignificant portion of your labor force. in 2017 35.7M Americans over 55 are in the labor force. As of 2019 there are 130.6M Americans in the labor force. So a little over 25% of the the workforce is 55+.
The other issue is it simply spreads too fast. if you allow it to run it replicates at a rate that keeps you from being able to maintain business as usual.
In a best case scenario (where the flu has a transmission rate of 1.3 and COVID19 has a transmission rate of 2.6) by the 10th generation 1 person with COVID19 has infected 1000X the number of people as one person with the flu will (14,000 vs 14). Keep in mind we vaccinate over 100M American adults each year- removing 50-80% of them (depending upon how good the vaccination is in a given year) from being potential spreaders and significantly lowering the R0 so it is manageable. We would not have to ability to do that with COVID19.
Most US cities in the 1918 Pandemic that had mitigation measures in place and then discontinued them before the first wave was almost down to zero got overrun with a larger second wave that ended up causing more long term economic damage.
Finally, no infectious disease has ever been brought to herd immunity level through natural herd immunity. Herd immunity to any infectious diseases has only been accomplished through vaccination programs.
So it all sounds great except for a few minor details.
1. Logistically it is impossible to isolate 68.7M Americans, much less the 110M that would likely be required.
2. In order to handle herd immunity, the testing has to exist and be in place.
3. You would first need to understand whether having the virus grants you immunity and if so for how long. Most previous Coronavirus' immunity, if there is any at all, tend to last months to a couple of years at most. So you could go through the whole herd immunity idea and then simply have to redo it in a year or two.
4. Economically natural herd immunity puts too many people out of work and lowers purchasing power too much to sustain.
5. Due to the high transmission rate our health and economic systems would likely be overrun within a couple of months.
https://www.jhsph.edu/covid-19/articles/achieving-herd-immunity-with-covid19.html