I don't know very well what medicine is about, but if you have some general knowledge in etiology or social epidemiology, then sociology of health, which is my research area, is a pretty good match to you. In addition, some basic idea about stats or biostats is also preferable.
One of the fast growing branch in sociology in recent years is to combine gene studies and sociology theory to fully understand why people get diseased and why some not others. It's a pretty interesting area and is indeed interdisciplinary, which I think is also very promising in uncover many mechanisms. UNC and Duke are very strong in this regard.