Exploring the feelings of being at risk of vaccine related adverse effects: A cross-sectional survey in France.

OBJECTIVES: The literature on vaccine hesitancy has widely commented on the various factors leading some to feel particularly at risk of disease infection while others do not. But little attention has been paid to whether we also see such differences regarding people's assessment of their personal vulnerability towards vaccine adverse events (AEs). METHODS: We designed two cross-sectional online surveys among representative samples of the French mainland population (n = 2015 and 3087). We asked participants if they felt, more than others, at risk of severe vaccine related side effects and to explain why. We performed two separate mixed effect binomial regressions models: 1) to explore the link between the feeling of being particularly at risk of severe vaccine related AEs and socio-demographic characteristics, source of information, trust in health agencies and partisan orientation; 2) to explore the link between the fear of side effects and vaccine hesitancy. RESULTS: We found that 15% of respondents felt to be, more than others, at risk of severe vaccine-related adverse events and that this feeling was associated to negative attitudes to vaccines. This feeling was particularly prevalent among women, those with a lower income, lower educational attainment and lower trust in public health institutions. The vast majority of the reasons given by responders are unrelated to genuine risk factors of vaccine related adverse events. CONCLUSIONS: These findings suggest that vaccine hesitancy is at least partly grounded in a feeling of vulnerability towards vaccine adverse events.

Impact of Vaccine Hesitancy on Onset, Severity and Type of Self-reported Adverse Events: A French Cross-Sectional Survey.

INTRODUCTION: Little is known about the impact of mandatory vaccination on people who are reluctant to be vaccinated, despite the potential importance in terms of public health policy. OBJECTIVE: We aimed to explore the relationship between vaccine hesitancy and onset, severity and characteristics of self-reported adverse events. METHODS: We used a cross-sectional online survey conducted in 2021 among a representative sample of the French population aged 18 years and older (n = 1593). All reported adverse events were analyzed and categorized by trained experts in drug safety and pharmacovigilance. Multivariate binomial regressions on the onset of self-reported adverse events, vaccine hesitancy categories and predefined responders' characteristics were performed. RESULTS: Overall, 590 (37.0%) participants reported at least one adverse event, with 121 (20.5%) considered it to be severe. Proportions of reported adverse events, ranging from 18% (in non-reluctant responders) to 65% (in very reluctant responders), and their severity, ranging from 5% (non-reluctant responders) to 41% (very reluctant responders), depended highly on attitudes toward vaccination. The adverse events profile remained similar between groups. In the multivariate regression model, beyond attitude toward vaccination, younger age and female gender were significantly associated with higher reporting of vaccine adverse events. CONCLUSIONS: Our results suggest that vaccine hesitancy could be a major driver of patient-reported vaccine-related adverse events and their perceived severity. In this context, vaccinators must pay special attention to reluctant patients and inform them on the possible nocebo nature of these adverse events so as to prevent them.