Despite widely recognised effectiveness against the spread of COVID-19, vaccine hesitancy persists. This systematic literature review aimed to clarify the definition and the operationalisation of the term 'vaccine hesitancy' and disclose the various psychosocial factors underlying this phenomenon. The results of studies conducted in European countries and in the United States after the vaccines became available were taken into account. The review was conducted according to the Preferred Reporting Items for Systematic Review and Meta-Analyses statement. Twelve studies met the inclusion criteria and were reviewed. efinitions and measures of vaccine hesitancy differed across the studies, limiting their comparison. Nonetheless, by drawing on theoretical frameworks, we were able to identify several psychosocial variables in determining vaccine hesitancy. Our findings point to the need for a transdisciplinary approach to understanding the antecedents of vaccine hesitancy. A better understanding of the phenomenon may help to develop interventions and social policies to address a complex challenge such as vaccination hesitancy.

Keywords: COVID‐19; Europe; USA; psychosocial variables; systematic review; vaccine; vaccine hesitancy.

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