Using Proportion of Similar Response (PSR) to Evaluate Correlates of Protection for Vaccine Efficacy

• Activity Number: 513
• Type: Contributed
• Date/Time: Wednesday, August 4, 2010 : 10:30 AM to 12:20 PM
• Sponsor: Biopharmaceutical Section
• Author(s): Katherine Giacoletti*+ and Joseph Heyse
• Companies: Merck & Co., Inc. and Merck Research Laboratories
• Keywords: Efficacy ; Non-parametric ; Overlap ; Vaccine

Abstract

The Proportion of Similar Response (PSR) method will be proposed as a way to address the question of whether serum antibody level is a sufficiently strong predictor of the risk of breakthrough disease to be used to classify vaccinees as protected or not, a key issue in many vaccine development programs. Traditionally, analyses to answer this question have been based on modeling the probability of developing breakthrough disease as a function of antibody level, among vaccinated subjects in a clinical development program. In addition, the relationships among PSR and other measures of overlap and discrimination will be described and the relative merits in the application to correlates of vaccine efficacy discussed. Further, the choice of a threshold level of protection will be discussed. An example based on a vaccine clinical trial will be presented.