Scaling up population health interventions from decision to sustainability - a window of opportunity? A qualitative view from policy-makers.

Much like Kingdon's Multiple Streams Theory of 'policy windows', there is a conceptually similar 'window for scale-up', driven by a complex interplay of factors such as political need, strategic context, funding and key actors. Researchers and policy-makers need to consider scalability from the outset and prepare for when the window for scale-up opens. Decision-makers need to provide longer term funding for scale-up to facilitate longer term sustainability and build on the resources already invested for the scale-up process.