Bridging Studies for WHO Pn ELISA
Peter C. Giardina, Pfizer Inc.  *Charles Tan, Pfizer 


The measurement of serotype-specific anti-capsular polysaccharide antibodies has been and remains the mainstay of pneumococcal (Pn) vaccine evaluation. New method formats that allow the simultaneous measurement of antibodies to several antigens in small volumes of serum are urgently required to support the development of extended-valency Pn vaccines, especially for infant populations. Bridging studies are required to evaluate how well the new method formats agree in terms of technical measurement characteristics. Potential implications for clinical use of the new method format also have to be assessed. Goldblatt et al (2011) described a study that compared a new multiplexed method for measuring anti-Pn antibodies with the existing WHO consensus enzyme-linked immunosorbent assay (ELISA). In this presentation, we’ll review the experimental and statistical methodology used to compare an additional multiplexed assay format to the WHO ELISA format. Potential enhancements to be considered for design and analysis of future bridging studies are discussed.