Table 1. Key advantages and challenges for different modes of secondary data sharing.

Mode of sharing	Advantages	Challenges
Direct sharing	Promotes wide re-use and repurposing of data and biospecimens for new insights.	Ensuring equitable agreements and negotiating benefit sharing is difficult, there is no oversight of onward use of resources.
Collaborative analysis	Generates large datasets with statistical power to make new inferences; allow oversight by data generators ensuring ethical onward use of data.	Collaborations can be difficult to set up; consensus may be tricky for authorship roles, attribution; IP may be difficult to assign.Data may be difficult to harmonise and combine.
Federated analysis	Can make use of resources that might not otherwise be shared due to incomplete consent or sensitive data.	Cross-dataset validation may be difficult; consensus may be tricky for authorship roles, attribution; IP may be difficult to assign.
Trusted research ecosystem	Sensitive data are not exposed and cannot be inappropriately shared or used.	Significant investments are required to set up and maintain infrastructure, governance and oversight of TREs.

IP, intellectual property; TRE, trusted research environment.