COVID and Simpson’s Paradox: Why So Many Vaccinated People are Among the Current Wave of Hospitalizations




There you have it — for this slice of time, the beginning of August 2021, Israel shows that the vaccines reduced risk 80%+, for all age groups.

Yes, if you just do an aggregation at the whole population level, it looks like a 67% reduction. That’s the “magic” of Simpson’s Paradox. For any given age group, the percentage reduction is much larger. But due to the relative risks by age, even with such high reductions, the overall population result shows a smaller improvement.

Takeaway: COVID vaccines greatly reduce risk

This is the main takeaway: the COVID vaccines greatly reduce the risk of adverse outcomes.

By the way, this is also true of the annual flu vaccines, which range in efficacy based on how well the vaccine that year matches up with the strains circulating, and which strains are circulating (some strains, even if you formulated the vaccine perfectly, still infect.) I could give you flu/pneumonia death rates by age groups, and you would see that flu/pneumonia is a big killer of the elderly. Get your flu vaccines, please.

But, we should also expect a lot of people hospitalized with COVID to be vaccinated old folks. Just because of the huge risk slope by age, which will still exist after vaccination.

Author(s): Mary Pat Campbell

Publication Date: 19 August 2021

Publication Site: STUMP at substack