Fig. 5From: Understanding how, why, for whom, and under what circumstances opt-out blood-borne virus testing programmes work to increase test engagement and uptake within prison: a rapid-realist reviewExample causal chain, with various intermediary outcomes that lead to the final outcome of public health interest. Each intermediary outcome forms the context of a subsequent programme theory. This casual chain operates between two spheres of context, detailed in Fig. 3 (the “Specific prison Context” and the “Programme implementation context”)Back to article page