Bridging Studies for Assays used in Vaccine Clinical Trials
*Tsai-Lien Lin, FDA 


As efficacy trials for many vaccines have become or are becoming unfeasible, demonstration of vaccine efficacy relies heavily on the immunogenicity endpoints. Bridging studies are often needed for assays used to measure antibody levels before and after vaccination. This presentation will provide an overview of various situations where bridging studies are conducted and appropriate questions that should be addressed under different situations. The challenge of linking a new assay to a previously established correlate of protection will be discussed. Real examples will be used to illustrate the issues, with a special focus on the assays for pneumococcal vaccines.