When I was learning about interpreting research, one of the things that we were always taught to be careful about is confirmation bias.
The example that is often used is throwing a newspaper at a dog when they're doing something bad. As long as the dog doesn't see the source of the newspaper, the dog begins to believe, "When I pee on the rug, a newspaper will fall out of the sky and hit me in the head, therefore to avoid getting in the head by a newspaper, I should not pee on the rug". Just because two events happen, it doesn't mean that there's an actual relationship between the two events or that one causes the other.
If I were to read a study that said that, "We found cases where people who received the COVID-19 vaccine were later diagnosed with multiple sclerosis", I might conclude that the vaccine caused COVID-19.
What is missing are some related questions:
- What is the incidence of MS in the general population? What is the incidence of MS in the group of people who got the vaccine? The answer is about 1 in 333 people have MS. That's a pretty high incidence, even before COVID-19 was discovered in 2020.
- What was the size of the population in the studies? One of the studies that was cited had 5 patients. When that study was published in Jan, 2022, over 9 BILLION people had received COVID-19 vaccines worldwide.
- Was there an explainable physiological cause that would explain why a COVID-19 might trigger MS in someone who had not previously been vaccinated? Did the population of people who developed MS have another possible causes in common (i.e. did they have mono? did they receive other vaccines like the flu vaccine? Did they have another viral infection during that period?).
Experts in auto-immune diseases and neurological disease had similar questions to my questions. And they concluded that the link between COVID-19 vaccines and multiple sclerosis was likely to be rare, random and weak. They also pointed out the same thing that I did:
people who get COVID-19 infections are more likely to develop MS than people who received the COVID-19 vaccines.
False. A database on the WHO website includes an abstract for a conference presentation about research that examined two recent cases of MS.
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