Dr. M. Elizabeth Halloran (University of Washington)

Title: The Minicommunity Design to Assess Indirect Effects of Vaccination

ABSTRACT: We propose the minicommunity design to estimate indirect effects of vaccination. Establishing indirect effects of vaccination in unvaccinated subpopulations could have important implications for global vaccine policies. In the minicommunity design, the household or other small transmission unit serves as the cluster in which to estimate indirect effects of vaccination, similar to studies in larger communities to estimate indirect, total, and overall effects. Examples from the literature include studies in small transmission units to estimate indirect effects of pertussis, pneumococcal, influenza, and cholera vaccines. The minicommunity study for indirect effects is contrasted with studies to estimate vaccine effects on infectiousness and protective effects under conditions of household exposure within small transmission units. The minicommunity design can be easily implemented in individually randomized studies by enrolling and following members of households of the randomized individuals. We show how these studies are developed in the framework of causal inference with interference. We will also show one or two microsimulations of vaccination programs for infectious diseases.