Study shows nocebo effect may influence the side effects of the COVID-19 vaccine

People's negative expectations and general attitudes towards the COVID-19 vaccine are significantly correlated with the occurrence and intensity of its most common side effects such as fatigue, muscle pain, headache and injection site pain.

This is suggested by a study published in the Psychological Science journal and led by scientists from the University of Bologna, who investigated how adverse effects reported after vaccination can be influenced by the nocebo effect, the opposite of the placebo effect.

A team of scientists from the Department of Medical and Surgical Sciences at the University of Bologna, in collaboration with a number of international research laboratories, decided to investigate whether and to what extent fear, expectations and beliefs about the vaccine have an effect on the occurrence and severity of possible adverse effects. This is referred to as the 'nocebo effect', a phenomenon that occurs as a consequence of negative expectations and beliefs, which can activate or reinforce possible side effects.

The researchers took a sample of 315 people and, during the 15-minute waiting time following vaccination, investigated their expectations, fears and beliefs about the COVID-19 vaccine, their trust in health and scientific institutions, and certain personality traits.

“The most relevant finding to emerge from this study is that psychological factors, such as an individual's beliefs and attitude towards the COVID-19 vaccine, contribute significantly to the onset and severity of adverse effects and explain 30% of the variability in their onset and intensity," said study author.

The data collected showed that the reported symptoms could not always be explained solely by the pharmacological and biological properties of the COVID-19 vaccine, thus showing the role of the nocebo effect.

Reference:

No(cebo) Vax: COVID-19 Vaccine Beliefs Are Important Determinants of Both Occurrence and Perceived Severity of Common Vaccines’ Adverse Effects,Psychological Science, DOI 10.1177/09567976231163875