One group receives an injection of vaccine, the other an ineffective placebo – this is how vaccine studies are structured. But even in the placebo group, people keep complaining about supposed vaccination reactions, including headaches. Why?
Slight headaches, feeling unwell, tiredness – such reactions are to be expected after a vaccination and show that the body’s immune system is dealing with the vaccine. But even after injections with saline solutions, i.e. placebos, supposed vaccination reactions are often reported in vaccine studies. In the studies, the participants do not know whether they received the vaccine or the placebo. This is important to study the effectiveness of the vaccine.
What are the apparent side effects? Researchers have investigated this question by evaluating the data from several corona vaccine studies. A large part of the perceived vaccination reactions could have their origin in the so-called nocebo effect.
The researchers analyzed twelve clinical studies with different corona vaccines. In total, the data included more than 45,300 participants who reported vaccination reactions – around 22,800 who had received vaccine injections and around 22,500 who had received a dummy preparation, i.e. saline solution. After the first dose, around 35 percent of the placebo recipients reported vaccination reactions such as headaches or fatigue. After the second dose, it was around 32 percent. For vaccine recipients, it was around 46 percent after the first dose and around 61 percent after the second dose.
Nocebo reactions account for most of the reports
According to the researchers, around three quarters (76 percent) of patient reports of general reactions such as headaches and fatigue can be traced back to nocebo reactions after the first vaccination dose. The effect was also evident after the second vaccination dose, albeit less strongly (51.8 percent). The results of the study were published in the specialist journal.
Placebo and nocebo effects are well known in medicine. Positive expectations can increase the effectiveness of a drug and even lead to an effect with a dummy drug – this is called the placebo effect. Conversely, with the nocebo effect, the expectation of negative consequences alone ensures that these are actually felt. The effect is known, for example, from the side effects listed on the package inserts for tablets: the mere expectation of a negative result can actually trigger pain or discomfort.
The reported vaccination symptoms (headache, fatigue) also occur quite frequently in everyday life and could be mistakenly associated with the injection. In this case, there would be a temporal connection (headache after vaccination), but no cause-effect relationship.
According to the scientists, the reason for the nocebo reactions could be the listing of possible consequences before the vaccination. “There is some evidence that this type of information can lead people to then mistakenly attribute common daily background sensations to the vaccine, or trigger anxiety and nervousness that make people very sensitive to possible side effects,” he said Study involved medical professor Ted Kaptchuk from Harvard Medical School
How could this knowledge be used in the future?
The researchers are discussing a more comprehensive education strategy: In the future, patients could be better informed about possible nocebo reactions before vaccination. For example, you could be told that people who received only placebo in trials reported similar vaccine responses to those who actually received vaccine, probably because of worry and anxiety. It could also be emphasized that sometimes no vaccination reactions are to be expected. According to the researchers, this type of additional information could help to reduce fears or reservations about the vaccination. “Medicine is based on trust,” says Kaptchuk.
Source From: Stern
