ABSTRACT
INTRODUCTION: Increases in global childhood vaccine delivery have led to decreases in morbidity from vaccine-preventable diseases. However, these improvements in vaccination have been heterogeneous, with some countries demonstrating greater levels of change and sustainability. Understanding what these high-performing countries have done differently and how their decision-making processes will support targeted improvements in childhood vaccine delivery. METHODS AND ANALYSIS: We studied three countries-Nepal, Senegal, Zambia-with exemplary improvements in coverage between 2000 and 2018 as part of the Exemplars in Global Health Programme. We apply established implementation science frameworks to understand the 'how' and 'why' underlying improvements in vaccine delivery and coverage. Through mixed-methods research, we will identify drivers of catalytic change in vaccine coverage and the decision-making process supporting these interventions and activities. Methods include quantitative analysis of available datasets and in-depth interviews and focus groups with key stakeholders in the global, national and subnational government and non-governmental organisation space, as well as community members and local health delivery system personnel. ETHICS AND DISSEMINATION: Working as a multinational and multidisciplinary team, and under oversight from all partner and national-level (where applicable) institutional review boards, we collect data from participants who provided informed consent. Findings are disseminated through a variety of forms, including peer-reviewed manuscripts related to country-specific case studies and vaccine system domain-specific analyses, presentations to key stakeholders in the global vaccine delivery space and narrative dissemination on the Exemplars.Health website.