Abstract
INTRODUCTION: Understanding barriers to childhood vaccination is crucial to inform effective interventions for maximising uptake. Published systematic reviews include different primary studies, producing varying lists of barriers. To make sense of this diverse body of literature, a comprehensive level of summary and synthesis is necessary. This overview of systematic reviews maps all potential parent-level barriers to childhood vaccination identified in systematic reviews. It synthesises these into a conceptual framework to inform development of a vaccine barriers assessment tool. METHODS: We applied Joanna Briggs methodology, searching the Epistemonikos review database and reference lists of included reviews to June 2020. Systematic reviews of qualitative or quantitative data on parent-level barriers to routine vaccination in preschool-aged children were included. Reviews addressing influenza, reporting non-modifiable determinants or reporting barriers not relevant to parents were excluded. Where possible, we extracted review details, barrier descriptions and the number, setting and design of primary studies. Two authors independently screened search results and inductively coded barrier descriptions. RESULTS: We screened 464 papers, identifying 30 relevant reviews with minimal overlap. Fourteen reviews included qualitative and quantitative primary studies, seven included quantitative and seven included qualitative studies only. Two did not report included study designs. Two-thirds of reviews (n=20; 67%) only included primary studies from high-income countries. We extracted 573 barrier descriptions and inductively coded these into 64 unique barriers in six overarching categories: (1) Access, (2) Clinic or Health System Barriers, (3) Concerns and Beliefs, (4) Health Perceptions and Experiences, (5) Knowledge and Information and (6) Social or Family Influence. CONCLUSIONS: A global overview of systematic reviews of parent-level barriers to childhood vaccine uptake identified 64 barriers to inform development of a new comprehensive survey instrument. This instrument will assess both access and acceptance barriers to more accurately diagnose the reasons for under-vaccination in children in different settings.