The human mind has amazing powers. But on the one hand, this can have a negative impact, one of which is if there is a nocebo, a side effect of the COVID-19 vaccine due to thoughts.
According to a recent study involving more than 45,000 patients, most of the adverse reactions people experience after a COVID-19 vaccination can be due to the nocebo effect.
What is a nocebo? The nocebo effect is a condition in which a person experiences side effects or negative symptoms from a treatment, caused by perceptions, suggestions, or beliefs that he continues to think about.
In a meta-analysis of 12 randomized placebo-controlled clinical trials, the research team at Beth Israel Deaconess Medical Center (BIDMC) in Boston found that 64% of vaccine side effects may be due to individual thoughts or suggestions.
"Side effects after placebo treatment are common in randomized controlled trials," said placebo researcher Julia W Haas of BIDMC, quoted from Science Alert, Friday (21/1/2022).
"Gathering systematic evidence of this nocebo response in vaccine trials is critical for COVID-19 vaccination worldwide, especially as concerns about side effects are reported to be a reason for vaccine doubt."
The 12 clinical trials studied by the team included a total of 45,380 patients. Of these, 22,802 were given the original vaccine. The rest, 22,578 patients were given a placebo, which is a harmless substance without a therapeutic effect like saline. Neither of the patients knew whether they were given the vaccine or a placebo.
After the first injection, 46.3% of vaccine patients reported systemic side effects, affecting the whole body, most commonly headache and fatigue. In a higher proportion of patients, 66.7% reported local side effects such as pain or swelling at the injection site.
Placebo patients also experienced adverse events, with 35.2% reporting systemic effects, and 16.2% reporting local effects. According to the team's analysis, comparing the ratio between the two groups, the nocebo effect accounted for up to 76% of systemic side effects and 24% of local side effects after the first vaccine dose.
However, this number dropped for the second dose. Fewer placebo patients reported adverse events, namely 31.8% for systemic effects and 11.8% for local effects. For vaccine recipients, these side effects were increased, with 61.4% of patients reporting systemic effects and 72.8% reporting local effects.
Overall, it shows that up to 52% of negative reactions after the second dose are due to the nocebo effect. In total, this means that 64% of all adverse reactions can be caused by the nocebo effect. Researchers think we may be able to overcome this.
"Non-specific symptoms such as headache and fatigue, which we demonstrated to be highly sensitive to nocebo, are listed as the most common adverse reactions after COVID-19 vaccination in many information leaflets," said placebo researcher Ted J. Kaptchuk of BIDMC and Harvard Medical School.
"Evidence suggests that this kind of information can cause people to misinterpret common sensations arising from vaccines or cause anxiety and worry that makes people very wary of how the body feels about adverse effects."
In previous research, the team has shown that communicating openly with patients can improve improvement in these conditions, especially regarding placebo medications, which are sometimes prescribed as treatment.
