CORONAVIRUS – Just because it’s “in the head” doesn’t mean the pain or fever isn’t real. The nocebo effect, less well known than its “positive” equivalent, the placebo effect, is a clinical reality, as an American study has just shown, which estimates that 76% of the side effects reported after a first vaccination against Covid would be the result.
What is the nocebo effect? As you can see in the video at the top of this article, like the placebo, it is a trick that our brain plays on us. We read about the side effects of taking a drug, and while worrying about having the misfortune to suffer from it, we actually develop the symptoms.
Difficult to measure, this somatization has been much studied recently. A study cited in the Smithsonian Magazine American, for example, showed that patients informed that a drug risked causing erectile problems in them, actually reported 47% of them. In the control group, the one who did not receive this information, only 15% of patients reported erectile problems to the doctor.
The role of our brain in the appearance of very real symptoms is an area still little studied, but the nocebo effect is now increasingly scrutinized. This is how the Boston team, by carrying out a randomized controlled trial, came to the conclusion that a large part of the symptoms reported after a first vaccination were linked to the list of side effects as they were presented before being vaccinated.
The experience, reported in the scientific journal JAMA on January 18, consisted of injecting a placebo into a group, and collecting information from another group of equivalent size (approximately 22,000 people), this one having actually been vaccinated. By comparing data from two groups, the research team concluded that three quarters of the side effects reported were due to the nocebo effect. A factor to be taken into account, conclude the authors, “in public health policies”.
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