Updated: Feb 24
US researchers have determined that most side effects people experience after COVID-19 vaccination are the product of the 'Nocebo effect' – an experience that occurs when negative expectations of the patient cause the treatment to have a more negative effect than it otherwise would have. Opposite the well-known placebo effect, an example of the 'Nocebo effect' is heightened pain if someone anticipates that something will hurt.
After reviewing 12 randomized clinical trials of COVID-19 vaccination, researchers found that the 'Nocebo effect' accounted for 76% of common adverse reactions, such as headache and fatigue, after the first dose; and nearly 52% after the second dose. Since these are the most discussed adverse reactions after a shot provided in COVID-19 vaccine leaflets, people expect to experience these even without actual occurrence.
While these findings suggest too much information about side effects can cause people to misattribute common ailments to the vaccine, researchers believe elaborated information through better public information, such as education on 'Nocebo effect,' may reduce concerns causing hesitancy and improve the COVID-19 vaccination rate.