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Oct 15, 2021 25 tweets 7 min read Read on X
This paper came out recently, and it is HUGELY popular among anti-vaccine advocates who are using it to suggest that vaccines don't work

It's also very fundamentally flawed. I'm a bit surprised it was published. Some thoughts 1/n Image
2/n The paper is here, and it's basically a series of comparisons of publicly-available COVID case and vaccine data conducted by a Harvard professor and a high-school student (note-DO NOT BE MEAN TO THE STUDENT, NEVER BE MEAN TO STUDENTS)… Image
3/n The study is broken into 2 sections. In the first, the authors took @OurWorldInData info, comparing the previous 7 days of case data between countries by vaccine rates. They produced this graph, showing no relationship between vaccines and reported cases Image
4/n There are several fundamental mistakes with this analysis. The first one is a biggie - confirmed cases, as reported by countries, are a useless statistic by themselves
5/n This goes back to the very early days of the pandemic - cases are, by definition, a function of tests. Without tests, you don't confirm cases, and therefore this comparison makes no sense at all on its own
6/n Did this impact the author's graph?

Very clearly yes. For example, let's compare the country Georgia (5408 cases/mil) with some of the places with less than 50 cases/mil in the author's graph on case/testing numbers ImageImage
7/n So the y-axis of this figure is uninterpretable. Meaningless.

What about the x-axis? Image
8/n There are 2 ways you can become immune to COVID-19 - vaccines and PRIOR INFECTION

In some of these countries (India, Russia, USA etc) it's likely that upwards of 40% of the entire population is immune to COVID-19 because they've had the disease and recovered (or died)
9/n In other words, we might expect that in places like Brazil, where 1 in every ~350 people has died from COVID-19 since the pandemic began, there would be quite a bit of immunity even with relatively low vaccination rates
9.5/n So comparing places on case numbers without taking infection-induced immunity into account is nonsensical, unless for some reason you think that it does not prevent infections
10/n On top of this, we've got the issue of an arbitrary 7-day window. Angola looked really good if you downloaded the data on 3/09. It looks less good if you download the data today Image
11/n So the first graph is pretty much useless as evidence. What about the second bit of the analysis?

Well, the authors essentially did the same thing, but for US counties. They found no difference in cases in US counties by vaccination status ImageImage
12/n So vaccines didn't prevent cases in the US!

Except, well, there's issues here too. Let's look at the places that the authors explicitly mention in the text Image
13/n Going to the file that the authors used, from Healthdata dot gov, you can see some really weird things pop up. Chattahoochee, GA, has a population of 10,907, but has 30,233 people who are fully immunized Image
14/n Indeed, looking down the list, all three of the counties identified by name - Chatahoochee, Mckinley, and Arecibo - have vaccinated more people than live there by quite a wide margin Image
15/n Meanwhile, of the counties classified as "low" transmission have rates of vaccination not just below 20%, but close to 0%!

What's going on here? Image
16/n The answer appears, based on this excellent @jburnmurdoch thread, to be that in the US vaccine doses are recorded based on the county *where they are given* not where the person lives
17/n This actually explains those discrepancies very neatly. Arecibo Municipio, for example, contains a stadium listed as a mass vaccination site in Puerto Rico Image
18/n On top of this, we've got the same issue with picking an arbitrary 7-day window as before - the median population in a county from this spreadsheet is ~26k people, which means that small variations in case numbers make a big difference
19/n This is even more apparent when looking at those "low" transmission counties - the median population is ~1k people, with some counties having <100. Weekly variation makes a HUGE difference!
20/n For example, Mineral County, CO, pop 769 is a "low" transmission county on 9/2, but a week later on 9/9 it's a "high" transmission county because it reported...2 cases
21/n All in all, this analysis is a bit meaningless as well. Using a 7-day period is pointless, it again ignores infection-derived immunity, and the vaccine rates are clearly not correct by county
22/n Ultimately, I don't think this paper has much, if any, meaning, and it's kind of bizarre that it was published at all. It certainly proves nothing whatsoever about vaccines and their effectiveness
23/n Oh, also, these are the most basic issues in the paper. I didn't even get started on things like Non-Pharmaceutical Interventions, confounding, etc etc etc
24/n Worth noting that the authors' intentions were clearly not anti-vaccine per se, but I do think that the paper is nevertheless not sufficiently robust to actually conclude anything about vaccines Image

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More from @GidMK

Feb 20
Fascinating study.

What's particularly interesting is a finding that the authors don't really discuss in their conclusion. These results appear to show that gender affirming care is associated with a reduction in suicide risk 1/n
2/n The paper is a retrospective cohort study that compares young adults and some teens who were referred for gender related services in Finland with a cohort that was matched using age and sex. The median age in the study was 19, so the majority of the population are adults. Image
3/n The study is very limited. The authors had access to the Finnish registries which include a wide range of data, but chose to only correct their cohorts for age, sex, and number of psychiatric appointments prior to their inclusion in the cohort.
Read 11 tweets
Oct 26, 2023
These headlines have to be some of the most ridiculous I've seen in a while

The study tested 18 different PFAS in a tiny sample of 176 people. Of those, one had a barely significant association with thyroid cancer

This is genuinely just not news at all Image
Here's the study. I'm somewhat surprised it even got published if I'm honest. A tiny case-control study, they looked at 88 people with thyroid cancer and 88 controls…
Here are the main results. There was a single measured PFAS which had a 'significant' association with the cancer, the others just look a bit like noise to me Image
Read 7 tweets
Oct 11, 2023
A new study has gone viral for purportedly showing that running therapy had similar efficacy to medication for depression

Which is weird, because a) it's not a very good study and b) seems not to show that at all 1/n
2/n The study is here. The authors describe it as a "partially randomized patient preference design", which is a wildly misleading term. In practice, this is simply a cohort study, where ~90% of the patients self-selected into their preferred treatment…
3/n This is a big problem, because it means that there are likely confounding factors between the two groups (i.e. who is likely to choose running therapy over meds?). Instead of a useful, randomized trial, this is a very small (n=141) non-randomized paper
Read 15 tweets
Oct 6, 2023

The study showed that COVID-19 had, if anything, very few long-term issues for children! As a new father, I find this data very reassuring regarding #LongCovid in kids 1/n Image
2/n The study is here, it's a retrospective cohort comparing children aged 0-14 who had COVID-19 to a matched control using a database of primary care visits in Italy…
3/ The authors found that there was an increased risk of a range of diagnoses for the kids with COVID-19 after their acute disease, including things like runny noses, anxiety/depression, diarrhoea, etc Image
Read 13 tweets
Sep 20, 2023
This study has recently gone viral, with people saying that it shows that nearly 20% of highly vaccinated people get Long COVID

I don't think it's reasonable to draw these conclusions based on this research. Let's talk about bias 1/n Image
2/n The study is here. It is a survey of people who tested positive to COVID-19 in Western Australia from July-Aug 2022…
3/n This immediately gives us our first source of bias

We KNOW that most cases of COVID-19 were missed at this point in the pandemic, so we're only getting the sample of those people who were sick enough to go and get tested
Read 12 tweets
Sep 19, 2023
Long COVID remains relatively prevalent - about 3-6% of people report long-term symptoms right now

But a really interesting question is Long COVID INCIDENCE - i.e. your risk of getting LC if infected today

I think the data we've got is reassuring 1/n Image
2/n The best source on COVID-19 data is, I think, the Office for National Statistics (ONS) survey data in the UK

This data looks at the COVID-19 infection survey participants, a (now discontinued) national sample of people who reported having COVID-19…
2.5/n Just a note - all of these numbers are INCREDIBLY UNCERTAIN for reasons I'll explain below. I would not take these as anything other than very rough guesses, because the data is very hard to assess at this point
Read 22 tweets

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