The placebo effect is a fascinating area of research because it so well illustrates the power of the human mind. The word placebo means something like “will please.” This effect occurs when people’s health status improves after receiving a pill that does not contain medicinal agents. In this way, homeopathy could also have an effect on people, even if their medicines do not contain a detectable active ingredient.
However, the placebo effect also exists in reverse and is known as nocebo. Derived from the Latin “nocere” (to harm), it means “I will harm”. The nocebo effect occurs when a sham treatment has negative consequences, for example, when people often experience the expected side effects of a drug they have not received.
And it is even more complicated: even if patients have received a medical substance, there is often also a placebo or nocebo effect. This depends, of course, on each therapy and the different expectations that each patient has. For example, if you imagine or expect nausea after taking a medication, it will occur more often, although this effect is very difficult to measure.
Recently, a group of researchers from the United States and Germany systematically looked for nocebo effects in various COVID-19 vaccine studies. And found them. According to the study, published in the Journal of the American Medical Association (JAMA), approximately one in three subjects who had not received any vaccine complained of adverse reactions related to this.
COVID-19 vaccine or saline solution?
Julia Haas and Sarah Ballou, placebo experts at Harvard Medical School in Boston, Massachusetts, worked with Friederike Bender, a psychologist at the University of Marburg, Germany, and other medical experts from the United States to analyze twelve studies on vaccines against COVID-19 with a total of 45,380 subjects aged 16 or older. Of these, 22,578 received a placebo, which was usually a saline solution.
All studies had been completed before July 14, 2021. Those investigations in which control groups had received other vaccines or adjuvants were discarded from the beginning. Adjuvants are additives commonly contained in vaccines that are supposed to enhance their effect.
Many side effects have nothing to do with the vaccine
After the first dose, 35.2% of subjects who received a placebo reported systemic side effects, including headaches (19.3%) and fatigue (16.7%). These were also the most common systemic side effects.
16% complained of non-systemic local side effects. For example, arm stiffness, swelling, pain or inflammation at the injection site. And after the administration of the second dose of placebo, 31.8% said they had systemic side effects and 11.8% non-systemic local effects.
By comparison, observed side effects were more frequent among subjects who had actually received a vaccine: 46.3% reported systemic side effects and 66.7% reported local side effects after the first vaccination. After the second dose, these values increased to 61.4% systemic side effects and 72.8% local effects.
How much nocebo do vaccinated people experience?
As already mentioned, placebo and nocebo effects occur with every therapy, that is, also when patients receive effective medication. In light of the strong nocebo effects seen with vaccines, a compelling question arose for medical researchers: How strong is the nocebo effect really in vaccinated people? Is it possible to calculate the nocebo effects in the secondary effects of the vaccinated people?
The answer: yes, it is possible, as researchers Haas, Ballou, Bender and their fellow researchers discovered. To do this, they calculated the proportion of nocebo effects in the unvaccinated and transferred this proportion to the vaccinated. As a result, the researchers found that even in those who had received a vaccine, nocebo effects dominate the side effects.
Thus, after the first vaccination, 76% of systemic side effects are attributed to the nocebo effect and, for local side effects, 24.3%. After the second vaccination, these values decreased somewhat, but still reached 51.8% for systemic side effects and 16.2% for local side effects.
The observations indicate that the expectations of the vaccinated persons have a strong influence on the perception of possible side effects. However, it would be a mistake to conclude that side effects are mostly caused by the imagination. The placebo or nocebo effect itself produces objectively measurable symptoms.
In conclusion, many of the symptoms are mainly driven by the individual’s own expectations and not by the medication. But patients also have no way of knowing, even if they know exactly what they feel.
(ju / lgc)