Reciprocal innovation in implementation science and global health: reflections from the EXTRA-CVD (extending the HIV treatment cascade for cardiovascular disease prevention) study.

Reciprocal innovation, a model of sustained, multidirectional exchange in which health strategies are adapted, revisited, and refined across contexts, offers a compelling framework to rethink how implementation science can support global health equity by enabling dynamic, multidirectional learning across different contexts. Drawing on the EXTRA-CVD trial, a nurse-led cardiovascular disease prevention intervention designed to extend the HIV treatment cascade in United States (U.S.) HIV clinics, which adapted strategies informed by implementation research in Kenya and the U.S. Veterans Affairs health system, this perspective examines how reciprocal innovation can begin to emerge within existing research structures, as well as where opportunities for deeper exchange remain limited. We identify four operational domains of reciprocal innovation: care delivery strategies, end-user engagement, research methodologies, and research leadership and partnership. Across these domains, we describe how cross-context learning shaped intervention adaptation and site-level implementation in EXTRA-CVD, as well as missed opportunities where more intentional feedback, shared leadership, and methodological exchange could have strengthened multidirectional learning. Taken together, this work highlights both the potential and the practical challenges of reciprocal innovation in implementation research, emphasizing its role in moving beyond unidirectional knowledge transfer toward iterative, context-responsive learning. By embedding structures for iterative feedback, equity-centered governance, and multidirectional learning systems within research and implementation systems, future global partnerships can foster more inclusive, responsive, and sustainable health interventions.