Perspectives from EPI personnel on immunization programme performance in Kenya: a thematic, complex adaptive systems and leverage-points analysis

Abstract Immunisation system performance depends on effective service delivery and the generation of high-quality data to support planning and decision-making. With the recent scaling down of external health funding, Kenya must identify sustainable strategies to strengthen the resilience of its immunisation programme. We conducted a three-part qualitative study comprising thematic analysis, application of complex adaptive systems (CAS) theory, and the Meadows leverage-points framework. Thematic key personnel interviews were conducted with selected Essential Programme on Immunisation (EPI) personnel from 14 counties and sub-counties in Kenya to explore factors influencing immunisation system performance. Vaccine distribution, health workforce shortages and immunisation financing emerged as the dominant themes affecting immunisation performance. Analysis through a CAS lens revealed that reinforcing feedback loops were more dominant than balancing loops, suggesting that system dysfunctions were more influential than adaptive self-correcting mechanisms, resulting in a tendency toward negative system behaviour. Application of the Meadows framework showed that existing interventions were largely concentrated at lower leverage levels, which are more likely to generate short-term operational improvements, while higher-leverage interventions with the potential for long-term system transformation remained underutilised. We concluded that systems-thinking approaches offer a powerful framework for understanding and improving immunisation system performance. They facilitate the identification of vulnerabilities and bottlenecks, while informing the design of higher-leverage interventions capable of producing sustainable and transformative improvements across the system.