What are the barriers and enablers to the uptake of the HPV vaccine in Romania, Bulgaria and Croatia? A mixed methods systematic review.

Introduction: Eradication of human papillomavirus (HPV) is a global public health priority. It is linked to approximately 5% of all cancers, causing almost all cases of cervical cancer, nearly 90% of anal cancers and a significant proportion of oropharyngeal, penile, vaginal and vulval cancers.HPV vaccination can provide protection when 90% coverage is reached. However, many countries are yet to achieve this threshold. Uptake in Romania, Bulgaria and Croatia has been low historically, and although rates are increasing, vaccine coverage remains significantly lower than the recommended WHO rate of 90%. This systematic review sought to identify the barriers and enablers to HPV vaccine uptake in these three countries. Methods: The Joanna Briggs Institute (JBI) convergent integrated methodological framework for mixed methods systematic reviews was employed. Seven databases were searched from inception to April 2024. No restrictions were imposed on language or setting. All included studies were critically appraised with JBI Critical Appraisal tools. Data extraction was performed using standardised tools with an emphasis on equity, followed by data transformation and data synthesis. Each stage was conducted by two independent reviewers. Bronfenbrenner's socio-ecological model was applied as a theoretical lens. Results: A total of 402 findings from 31 studies were extracted and aggregated to form 65 categories. These were further combined in a meta-synthesis which yielded 13 synthesised findings. The meta synthesis identified commonalities across each country's findings: attitudes towards HPV vaccination were characterised by distrust and misconceptions; knowledge deficits existed particularly in relation to gender neutral provision; and a lack of consensus among health professionals concerning the efficacy and safety of the vaccine impacted intention and uptake. Conclusions: Barriers and enablers to HPV vaccine uptake centred on knowledge and trust. Public health interventions that address the concerns of young people, parents and health professionals are pivotal to improving HPV vaccine coverage across the three countries. Contemporaneous research to further explore the social, cultural and political factors that impede acceptance of the HPV vaccine is also required. PROSPERO registration number: CRD42024523200.