Vaccine hesitancy about COVID-19 vaccines is a positive predictor of negative side effects with vaccination—an example of the "nocebo" effect—according to a study today in Scientific Reports.
Nocebo, a play on placebo, is a phenomenon in which people experience negative effects on health when they have negative views or expectations surrounding medical interventions.
The study was based on surveys of a representative sample of 756 older Israeli adults (mean age, 69 years) who were questioned following a second Pfizer vaccine dose and after their booster at least 6 months later. Older adults were selected for the study because they have the highest vaccine uptake because they are most likely to suffer complications from COVID-19 infections, the authors said.
The authors found that hesitancy about the second Pfizer dose resulted in nocebo side effects for 16% of study participants. There were sex differences seen among those who reported side effects, with women reporting increasing side effects after both the second vaccine injection and the booster dose.
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