Abstract:

Despite substantial global progress in routine childhood immunisation, inequities persist, particularly among children living in urban informal settlements. Globally, an estimated 13 million children remain zero-dose each year—defined as children who have not received the first dose of a diphtheria–tetanus–pertussis (DTP)-containing vaccine. These children represent the most systematically excluded populations within immunisation systems and face the highest risk of vaccine-preventable diseases. In Uganda, rapid urbanisation has contributed to the concentration of zero-dose children in peri-urban districts such as Wakiso, where informal settlements are characterised by high population mobility, weak community–health facility linkages, and fragmented immunisation data systems. This study evaluates the effectiveness and implementation performance of a data-linked community–health facility strategy to improve identification, referral completion, and vaccination uptake among zero-dose and under-immunised children aged 0–23 months in urban informal settlements of Wakiso District, Uganda. A mixed-methods implementation research design will be used. Quantitative data will be obtained from routine immunisation records, household verification surveys, and integrated community registers, while qualitative data will be collected through focus group discussions and key informant interviews with caregivers, Village Health Teams, and health workers. Primary outcomes include changes in the identification and vaccination initiation of zero-dose children, measured through DTP1 uptake. Secondary outcomes include the acceptability, feasibility, and scalability of the intervention using the RE-AIM (Reach, Effectiveness, Adoption, Implementation and Maintenance) framework. By strengthening integration between community-generated data and health facility immunisation records, the study aims to generate practical implementation evidence for improving immunisation equity in urban informal settlements. Findings will inform district immunisation microplanning and outreach strategies. The study will also generate implementation-relevant evidence to support national immunisation policy and scalable approaches for identifying and reaching zero-dose children in rapidly urbanising settings.

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