You are not going to get off a waitlist until the adcom figures out that so many of their offers went unaccepted that they still have empty seats. Because so many people hold multiple offers until May, and because schools are still chosing their top choices, you must just bide your time.
From May until August, the adcom (or the Dean of Admissions) has the job of finding waitlisted applicants to fill empty seats. It is almost like finding a date for the prom. Some of those waitlisted applicants will have had offers from other med schools. Deans don't want to waste their time calling those applicants so they will call those who have signaled that they are available and interested. Your job come May is to signal that you are still available and still interested. Sometimes seats become available at the last minute due to all sorts of odd circumstances. If you are still waitlisted in August and you can move quickly if called, tell the Dean of Admissions. For now, just wait quietly.