During the period July‒December 2023, JSI, as the global learning partner, continued to provide technical assistance and collaborate and co-create with the Nigeria Learning Hub. This semiannual update for the Gavi, the Vaccine Alliance Board (Gavi Board) and other stakeholders highlights the Nigeria Learning Hub's efforts to leverage evidence for a deeper understanding of the factors that affect the implementation and performance of strategies to identify and reach ZD and under-immunized (UI) children and missed communities in Nigeria. It synthesizes findings, challenges, and recommendations emerging across the IRMMA framework.