On Stepped Wedge Designs for Vaccine Effectiveness Studies Under Complex Transmission Conditions

• Activity Number: 452
• Type: Contributed
• Date/Time: Wednesday, August 6, 2014 : 8:30 AM to 10:20 AM
• Sponsor: Section on Statistics in Epidemiology
• Author(s): Sahar Zangeneh*+ and M. Elizabeth Halloran and Ira Longini
• Companies: Fred Hutchinson Cancer Research Center and Fred Hutchinson Cancer Research Center and University of Florida
• Keywords: Community randomized trial ; stepped wedge design ; vaccine efficacy ; dynamics

Abstract

Community randomized trials, where the intervention is randomized to groups of individuals, can be used to evaluate the direct, indirect, total and overall effects of a vaccination strategy. Some Infectious diseases have complex transmission patterns, posing challenges to evaluating vaccination programs. Stepped wedge designs, where the clusters cross over from control to vaccine arm during the study, can be more acceptable to the public than parallel studies in which the entire control arm remains unvaccinated until the end of the study. We investigate properties of stepped wedge designs for vaccine effectiveness studies targeted to viruses with multiple competing strains in the presence of time-varying covariates, complex transmission patterns, seasonality, and duration limited by public acceptance. We compare and contrast such designs to commonly used parallel designs. We use simulated and demographic data from the state of the Yucatan in Mexico to design a stepwise introduction for evaluating the effectiveness of a tetravalent dengue vaccine.