Physical side effects of COVID-19 vaccine might be caused by the nocebo effect. A paper published in Psychological Science by an international research featuring Dr Joanna Kłosowska and Prof. Przemysław Bąbel from the Pain Research Group of the JU Institute of Psychology shows the effects of one’s personal opinions on the organism’s reaction to vaccine.
Pinning adverse effects of a vaccine on the opinions held by the inoculated person may at first seem an absurdity rather than a scientific fact. However, it can be argued that in some cases, this may be explained by the nocebo effect, the reverse of the placebo effect. Researchers from the JU Institute of Psychology say this phenomenon is very well described in psychological and medical literature. ‘The nocebo effect occurs when patients experience various negative symptoms after being administered with a neutral substance. It also means experiencing adverse effects of an active substance that are not at all related to its pharmacological properties. Our research suggests that a large portion of COVID-19 vaccine side effects may be explained by the nocebo effect’, say Dr Joanna Kłosowska and Prof. Przemysław Bąbel.
How do you feel?
The experiment had a total of 315 participants. During the fifteen minute waiting time period, they were asked about their fears, opinions and expectations regarding the COVID-19 vaccine as well as its possible side effects. Additionally, researchers asked them about their level of trust towards health care institutions and science as well as measured their stable personality traits, such as optimism. The incidence and intensity of ten potential adverse effects of the vaccine was assessed by the volunteers 24 hours later.
As it turned out, the patients’ expectations and attitude towards the vaccine, gauged just after inoculation, proved to be reliable indicators when it came to the incidence and intensity of side effects reported by them 24 hours later. How is this possible?
Learning… side effects
In the paper No(cebo) Vax: COVID-19 Vaccine Beliefs Are Important Determinants of Both Occurrence and Perceived Severity of Common Vaccines’ Adverse Effects, research explain that the nocebo effect is triggered by the same processes that are responsible for learning as well as expectations. Previous experiences with active substances that cause side effects or observing such side effects in others may induce the nocebo effect. Similarly, reading a leaflet or hearing a doctor or other patient describe adverse effects of a substance can have the same consequences. Previous experiences with side effects or information gathered from perceived authority figures or other vaccinated people lead to expectations of certain negative outcomes of vaccination. Such expectations, as shown through research, may translate into purely physical symptoms. There is also data indicating that conscious expectations are not required for the nocebo effect to occur. Previous experiences or observations of others cause it, to some extent, automatically. Additionally, there are other factors at play here, such as attention bias or interpretive bias. Patients that expect negative outcomes of vaccination are often overly focused on their bodies’ sensations, interpreting even neutral feelings in a negative way.
Widespread vaccination changed our lives for the better
The analysis published in Psychological Science leads to several conclusions. Firstly, effective education and information campaigns regarding the nocebo effect and vaccination safety lead to fewer adverse events following immunisation (AEFI). Secondly, building trust toward health care institutions and medicine in general is a crucial goal. In particular, it is important that people in direct contact with patients, such as primary care physicians, are open to discussion about side effects of vaccinations and dispel their doubts rather than ignore or mock them. It is also vital to reinforce a positive outlook on side effects: the experiment, as many others before, confirmed that the higher intensity of side effects, the stronger the immune response.
Attitude toward vaccines can be changed
‘This is a serious matter. Widespread public vaccination is one of the most important achievements of modern states and science. Thanks to coordinated efforts, diseases such as polio, measles and smallpox stopped running the health and lives of millions of people around the world. We need to make sure that the vaccination level stays sufficiently high. Our research shows how important non-pharmacological factors, including psychological issues, play in vaccine efficacy, and therefore, how important it is to use psychological knowledge to change attitudes toward vaccinations’, says Prof. Przemysław Bąbel.
