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Nocebo Effect - review

A recent article in The Guardian summarizing some research conducted into the adverse effects of COVID vaccines states: "More than two-thirds of the common side-effects people experience after a Covid jab can be attributed to a negative version of the placebo effect rather than the vaccine itself, researchers claim."


The side-effects they refer to are the less severe, non-specific ones such as headaches, short-term fatigue, and arm pain. These symptoms, according to the research, can be shown to be not caused by the "constituents of the vaccine" itself, but instead by factors like the feeling of trepidation and expectation that one experiences before receiving the vaccine, as well as incorrectly making a link between the vaccine and the symptoms. In other words, just because you feel tired after having the jab, it doesn't mean the former is caused by the latter.


The researchers refer to the 'nocebo effect', which is essentially the same as the placebo effect, but with regards to negative feelings and experiences, rather than the positive ones associated with placebos. The nocebo effect explains why people might feel negative or unpleasant symptoms, like headaches or arm pain, after receiving the vaccine, even though there is nothing in the vaccine itself, in terms of its chemical composition, that should cause such problems. See the entry on the placebo effect for more details about how this works.


However, it's important to remember that just because a symptom or experience is down to the nocebo (or placebo) effect, it is no less valid, or important, or serious. The "it's all in your head" mentality is not helpful. Whether or not there is a clear biochemical mechanism of action makes the negative experiences no less real. The placebo/nocebo effect has long been badly understood, or ignored, or derided in the world of medical research. Given the delicate nature of the COIVID vaccine discussion, it will help no one to be dismissive of this phenomenom.


Indeed, we should be frank and open to discussion of what the nocebo effect, without prejudice. As the preeminent scholar on the placcebo effect, Ted Kaptchuk, states in the article:

“'Most researchers argue that patients should be told less about side-effects to reduce their anxiety,' he said. 'I think this is wrong. Honesty is the way to go.'”




Accessed 12.2.2022

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