Background: The involvement of people living in situations of vulnerability has long been a central ethical issue in research, particularly in contexts marked by power asymmetries, limited access to resources, or restricted decisional autonomy. Although international ethical frameworks offer increasing guidance on protecting vulnerable participants, applying these principles in everyday research practice remains challenging, especially in qualitative and multi-country studies. This communication draws on the experience of the European Protecting You (b) participants’ self-perceptions and tensions between externally assigned vulnerability; (c) risks of stigmatization associated with categorization; the use of respectful and context-appropriate language; and (d) the adoption of a shared international framework adapted to educational content across countries. Overall, vulnerability emerged as a dynamic and context-dependent condition that requires research designs, methodologies and interventions to remain open, flexible, and responsive throughout the study process. Conclusions: Studies involving people living in situations of vulnerability, particularly in international and multi-country contexts, should not rely solely on predefined classifications or standardized safeguards. Instead, adaptive procedures are needed to recognize how needs, barriers, resources, and forms of participation vary across individuals and contexts. Such openness may support more person-centered approaches to engagement, communication, and intervention adaptation, while preserving ethical consistency and methodological rigor across countries.
Chiappinotto et al. (Sun,) studied this question.