Multi-Arm Superiority Tests for Vaccine Efficacy

This technical report discusses the computation of power and sample size for multi-arm superiority tests aimed at evaluating vaccine efficacy (VE) using the ratio of treatment and control proportions in a cluster-randomized design. The document outlines the definition of VE and the methodology for calculating it, emphasizing the importance of comparing multiple treatment groups against a control group. The report explains the implications of using cluster-randomized designs, where whole units are randomized, and details the challenges associated with sample size estimation in such studies. The report also addresses the concept of relative vaccine efficacy (rVE) and the necessity of applying multiplicity adjustments when conducting multiple hypothesis tests. Additionally, it provides technical details on statistical hypotheses, the transformation of VE values, and the significance of the design effect in sample size calculations. Overall, the report serves as a comprehensive guide for researchers designing vaccine efficacy trials.