The European Health Data Space: an opportunity to strengthen citizen rights and engage citizens in health data governance.

Introduction: The European Health Data Space (EHDS), the European Union's new regulatory framework for health data use and reuse, will have important implications for citizens across the Union. While the regulation aims to empower citizens in the primary use of their health data-such as by giving them access to their electronic health records-their role in the secondary use of health data remains less clearly defined. Methods: To explore this, we interviewed health data experts across 23 European countries to understand their perspectives on citizen involvement in data reuse. Results: Our findings reveal that while the provision for an opt-out mechanism provides individuals with control, its practical implementation requires careful design to ensure accessibility and operability. Experts also emphasized the importance of broader citizen engagement, both to raise awareness about the EHDS and to incorporate citizens' perspectives into governance structures. Furthermore, clearly demonstrating the value of the EHDS was perceived to be crucial for fostering public trust and acceptance. Discussion: The study provides valuable insights for Member States in developing strategies to engage citizens in the secondary use of health data under the EHDS framework. It highlights the importance of an easily accessible opt-out mechanism, reinforced by clear and effective communication to prevent misinformation, emphasize the tangible benefits of data sharing, and account for the influence of institutional trust and country-specific contexts in shaping public attitudes toward the EHDS.