Contextual factors shaping the delivery of routine immunisation services in the Mumbunda Health Zone, Democratic Republic of the Congo: a multiple case study of head nurses' experiences

Objectives: To analyse how contextual factors shape the delivery of routine Expanded Programme on Immunisation (EPI) services in the urban Mumbunda Health Zone, Democratic Republic of the Congo, from the perspective of head nurses. Design: Multiple case study conducted from May to June 2026. Setting: Seven health areas in the urban Mumbunda Health Zone, Democratic Republic of the Congo. Participants: Seven head nurses selected purposively; four participants took part in additional follow-up interviews. Methods: Semi-structured individual interviews were analysed using reflexive thematic analysis, with systematic within-case and cross-case comparisons. Findings were organised using the four contextual dimensions of Leichter's framework. Results: Nine subthemes and one cross-cutting theme were identified. Situational factors comprised population mobility, seasonality and time constraints that affected access to, and monitoring of, immunisation. Structural factors included peripheral governance, microplanning and information flows; functional staff availability; operational and logistical resources; and community organisation. Cultural factors included professional norms, variable uptake of EPI requirements, perceptions of vaccination and language-related influences on trust. Exogenous factors reflected dependence on decisions at health-zone level and on external resources, alongside the transfer of some routine costs to facilities and health workers. Across all four dimensions, participants described compensatory local adaptations that helped sustain service delivery despite these constraints. Conclusions: Strengthening routine immunisation requires participatory microplanning, predictable financing for routine operational costs and context-sensitive support for facility teams and community health workers. Policy should enable useful local adaptation while reducing reliance on health workers' personal resources to sustain day-to-day service delivery. Strengths and limitations of this study The multiple case design enabled systematic examination of similarities and differences within and across seven health areas in the same urban health zone. Follow-up interviews with four participants were used to clarify, elaborate and refine their accounts. Leichter's framework provided an explicit structure for analysing contextual factors while allowing a cross-cutting theme to emerge inductively. The findings reflect the perspectives of seven head nurses and do not directly represent those of other EPI stakeholders. Data were collected in a single health zone over a limited period, restricting examination of variation across settings and over time.