We will use the findings from Phases 1 and 2, in accordance with guidelines on complex intervention development, to develop context-appropriate interventions to increase coverage of essential emergency and critical care (EECC). We will undertake a pilot implementation in four African countries with health economics analyses and mixed-methods process evaluations, including interviews with front-line healthcare staff, patients and community members to assess feasibility and perceptions around the intervention and assess the impact on costs and healthcare expenditures, allowing further development to ensure optimal design. The output will be an evidence-based complex intervention package, comprising both clinical and implementation science components, which facilitates the sustainable delivery of EECC in African hospitals.