C. Diff is highly contagious and can cause serious damage to the large intestine if left untreated. RCR is looking for healthy adults between the ages of 65 and 84 for this trial, aiming to find a more effective vaccine for preventing the spread of the C. Diff bacteria. Participating in this study will require 9 visits to our office over the course of a year, and compensation will be provided for your time and travel.