Challenges and opportunities in coproduction: reflections on working with young people to develop an intervention to prevent violence in informal settlements in South Africa.

Coproduction is widely recognised as essential to the development of effective and sustainable complex health interventions. Through involving potential end users in the design of interventions, coproduction provides a means of challenging power relations and ensuring the intervention being implemented accurately reflects lived experiences. Yet, how do we ensure that coproduction delivers on this promise? What methods or techniques can we use to challenge power relations and ensure interventions are both more effective and sustainable in the longer term? To answer these questions, we openly reflect on the coproduction process used as part of Siyaphambili Youth ('Youth Moving Forward'), a 3-year project to create an intervention to address the social contextual factors that create of health risks for young people living in informal settlements in KwaZulu-Natal province in South Africa. We identify four methods or techniques that may help improve the methodological practice of coproduction: (1) building trust through small group work with similar individuals, opportunities for distance from the research topic and mutual exchanges about lived experiences; (2) strengthening research capacity by involving end users in the interpretation of data and explaining research concepts in a way that is meaningful to them; (3) embracing conflicts that arise between researchers' perspectives and those of people with lived experiences; and (4) challenging research epistemologies through creating spaces for constant reflection by the research team. These methods are not a magic chalice of codeveloping complex health interventions, but rather an invitation for a wider conversation that moves beyond a set of principles to interrogate what works in coproduction practice. In order to move the conversation forward, we suggest that coproduction needs to be seen as its own complex intervention, with research teams as potential beneficiaries.