Had a brief but interesting exchange with Aaron Day yesterday. Unfortunately, it started with a post on a local Community Facebook page where the page admins generally remove any posts that are controversial. That generally includes everything related to COVID-19. Also unfortunately, the admins removed the posts before I could copy them, but I think I can re-create the general thrust of the "discussion" here, because it makes an interesting point.
The Scenario:
First, Aaron Day posted this, without comment (I apologize for the poor image quality. Aaron didn't post a link to his image and it appears to be a screen shot on a phone, so I assume he copied it from someone else):
When I first saw it, I thought perhaps Aaron Day was adding some evidence to counter that commonly used anti-vaxx story, that most of the people in hospital are vaccinated, without understanding what they're really seeing. Because, if you look at the last set of numbers in the image above, you will see exactly that. Unvaccinated people are represented in hospital 6 times more than vaccinated people IF you take into account the population that they come from.
So, I posted this image:
What my image shows, using some representative numbers just for explanatory purposes, is this:
The left circle shows 15 people hospitalized, 10 of whom are vaccinated. To the casual reader, this looks like 67% of hospitalizations are vaccinated people while 33% of hospitalizations are unvaccinated people. If that's where you stop, it certainly doesn't look good for vaccines.
However, if you move to the circles on the right side, you can see that the 10 vaccinated people who are hospitalized come from a much larger population than the 5 unvaccinated people in hospital. Even without further analysis, you can see what's starting to appear here.
So Aaron Day's response was to ask where I got the image I posted, at which time I invited him to move the discussion to my Facebook page where we could carry on a discussion that I knew local admins would not tolerate on the community page.
In a short time, I repeated the invitation. He refused, demanding to know "Where. Did. I. Get. My. Image. From." To my knowledge, he has not been able to bring himself to follow up on my invitation. He said my answer didn't need to be moved to a private location, but my posts are public, whereas his FB page has nothing on it at all.
For the record, my image was part of a longer article that appeared here:
And remember, my image only uses representative numbers to make a point. To see how this is playing out in your own area, you would need to use numbers from your jurisdiction. Which I have done, and which Aaron's original image did as well, although I don't think Aaron looked far enough into his numbers to understand.
So, back to my image. It shows a population that is approximately 90% vaccinated. So that's roughly representative of where we'd like to be, but BC right now, is only about 80% vaccinated. About 4.06 million out of a population of 5.07 million. For ease of calculation, I've ONLY included fully vaccinated, not partially vaccinated (which includes many children). We know that the vaccines aren't 100% effective. In the image above, with 90% effectiveness, some vaccinated are ending up in hospital, but if you do the math, you will see what Aaron's own post already showed - unvaccinated people are very over-represented in hospital when you take into account the size of the population they come from.
The Math:
So, using numbers from BC recently, keeping in mind that all the data needed isn't from exactly the same day. But ALL this data is readily available from a variety of sources.
About 80% of BC's population of 5.07 million is fully vaccinated. So, that's about 4.06 million people.
About 20% of BC's population of 5.07 million is unvaccinated, or at least not fully vaccinated. That's about 1.01 million people.
As of January 12. 2022, about 500 people were hospitalized and 102 of those were in ICU. There were 6 deaths in the preceding 24 hours.
As of January 5th, 2022, it was reported that about 50% of those hospitalized were unvaccinated, so, about 250 vaccinated and 250 unvaccinated.
So, taking the approach described above, 250 unvaccinated out of an unvaccinated population of 1.01 million equals 24 per 100,000 and 250 vaccinated out of a vaccinated population of 4.06 million equals 6 per 100,000.
So, unvaccinated people are 4x as likely to end up in hospital as vaccinated (even considering their relatively small numbers. That's 300% as likely, according to my handy Percentage Difference Calculator.
Note that I haven't taken into account the partially vaccinated at all. In my calculations, you're either fully vaccinated or you're not. If I were to take into account the partially vaccinated, who have some protection from the virus, and making the unvaccinated population even smaller, the situation would look even worse for the unvaccinated.
And I followed up with this comment to Aaron on my Facebook page:
"So, Aaron Day has commented that the graphic I posted above - the one with the circles and dots - is illegitimate. As I said from the beginning, the graphic is just representative of a process to help us understand Base Rate Bias. They are NOT real numbers from anywhere. I used real numbers from BC in my calculations above.
However, Aaron Day, you posted the following graphic [see his graphic above]:
Look at the last set of numbers where they have been adjusted to a number per 100,000. Just look at them. What do you see?
What I see is unvaccinated people being hospitalized at a rate over 6 times vaccinated people.
So, thank you for posting a graphic (data from a government website, as you say) that supports exactly what I've been saying all along. Just follow the last 2 or 3 posts here to see what I'm driving at.
And the set of numbers right above those, representing cases, makes one point very clearly. Yes, vaccinated people "can" get the virus and "can" test positive, but they aren't nearly as likely to end up in hospital, or, I assume, the ICU, or, even more importantly, dead."
Base Rate Fallacy, or Base Rate Bias, has been discussed before. This article explains it very well, too. Your Local Epidemiologist Just scroll down until you find the blue and red dots.
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