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I want to make sure we're all on the same page when we're talking about achieving herd immunity through natural infection. Important notes in 
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Fine Print: The model underlying this chart makes assumptions which parallel those made by proponents of herd immunity as a public health intervention to stop the spread of COVID-19. Several of these assumptions are 100% absurd, but here's what it looks like if we use them.
Specifically, we assume that:
- Once a person has had COVID-19 once, they can never get it again (that's not true, so in reality the number of cases needed to reach herd immunity is much higher than shown here--in fact we will never reach it through natural infection).
- Once a person has had COVID-19 once, they can never get it again (that's not true, so in reality the number of cases needed to reach herd immunity is much higher than shown here--in fact we will never reach it through natural infection).
- The “cases needed” estimate assumes that a total of 80% of people under age 65 must become immune through infection and that somehow only a total of 20% of people over age 65 become infected in the process. (This would be practically impossible to achieve.)
80%/20% approximate what is thought to be the herd immunity threshold for COVID-19, or the population level immunity at which the disease would no longer find readily available susceptible people.
- The model assumes that we have confirmed 1 out of every 5 cases of COVID-19 in Wisconsin so far. Or to put that another way, that for every case listed in the WI DHS case count, there are 4 more cases that were never diagnosed.
And in case we want to ignore morbidity entirely, here's what mortality looks like:
Mortality chart makes two more assumptions, namely that
- Age-specific infection fatality rates will be stable going forward, which implies that
- We won't run out of hospital beds, ventilators, staff, etc. as this unfolds, so deaths from COVID-19 & other causes won't spike
- Age-specific infection fatality rates will be stable going forward, which implies that
- We won't run out of hospital beds, ventilators, staff, etc. as this unfolds, so deaths from COVID-19 & other causes won't spike
Data sources: CDC’s pandemic scenario planning guidance, Wisconsin Department of Health Services, and Census American Community Survey 1-year population estimates from 2019.
I'm old enough to remember when the GOP was losing its collective mind about death panels.
We're not even close. Herd immunity through natural infection is unethical & impractical. And even if we were willing to throw ourselves on the pyre, it wouldn't work in any case. #JohnSnowMemorandum #IllWaitForAVaccineThankYou #HerdImmunityUnacceptable
I mean it's such a bad idea it would be hilarious if we weren't talking about people's lives.
