Determinants of vaccine hesitancy and interventions aimed at contrasting this issue in Europe: an overview of systematic reviews

Introduction. Vaccine hesitancy remains a major public health challenge in Europe, with declining confidence in vaccine safety and efficacy despite high overall acceptance. Evidence on its determinants and effective interventions is fragmented, underscoring the need for a comprehensive synthesis. This overview of systematic reviews aimed to describe the most recent determinants of vaccine acceptance, barriers to vaccination, and effective interventions to reduce hesitancy or increase uptake in Europe. Methods. The search was conducted in PubMed, Embase, Epistemonikos. Reviews were eligible if they included European data. Results. Of 3,363 papers, 88 reviews were included, classified into children, adolescents, and parents (n=29); pregnant women (n=11); healthcare workers (HCWs) (n=12); and the general population (n=36) reviews. Determinants of vaccine acceptance included high education, socioeconomic status, gender, trust in government/health authorities, and HCW recommendations, with associations that varied across populations, vaccines, and contexts. Emerging determinants such as health engagement and social media were reported. Main barriers included fear of side effects, safety concerns, preference for natural immunity, and logistical challenges. Interventions included educational campaigns, reminders, organizational changes, school-based programs, and digital tools. Active reminders, school-based programs, and organizational changes showed the most consistent effectiveness. Conclusions. Vaccine hesitancy is multifaceted, requiring tailored, evidence-based strategies. Future research should prioritize rigorous study designs and underexamined factors.