Shaping the future EHDS: recommendations for implementation of Health Data Access Bodies in the HealthData@EU infrastructure for secondary use of electronic health data.

European Union (EU) Member States face challenges in using health data for secondary purposes, constrained by inconsistent digital health systems and limited cross-border sharing. One aim of the European Health Data Space (EHDS) is to facilitate secondary health data use through the HealthData@EU infrastructure and Health Data Access Bodies (HDABs). This article provides recommendations essential for HDAB implementation, informed by the HealthData@EU Pilot project. From October 2022 to December 2024, Work Package 4 gathered insights from the HealthData@EU Pilot project, including from technical work packages and use cases, and complementary insights from the members of the HDABs Community of Practice and the External Advisory Board. Data collection involved workshops, interviews, and questionnaires, with thematic analysis guided by the EHDS user journey and the World Health Organization's National eHealth Strategy Toolkit. Recommendations cover infrastructure, services, and interoperability. Each Member State should designate HDABs to manage secondary health data use and facilitate cross-border access. National infrastructure components deployed by HDABs and National Contact Points and a metadata catalogue compliant with the newly developed HealthDCAT-AP specification are advised to support data discovery, with a common data access application form to streamline the data permit application process. Harmonized validation procedures are recommended for ensuring high data quality and semantic interoperability. Implementation of HDABs within the HealthData@EU infrastructure represents an important step towards accessible health data for secondary use across the EU. Effective implementation requires collaboration at both national and EU level, addressing remaining ambiguities for HDAB functionality within the EHDS framework.