On the off chance that people will come to this in the coming years, I just got accepted into the ISyE master's program for health systems, and my overall undergrad GPA was a 2.43, math major GPA being slightly above a 3.0, coming from University of Michigan (Ann Arbor) with an applied mathematics degree.
I will say that I have been working for the past 3 years though in a somewhat related line of research: disease transmission modeling, intervention resource allocation optimization, market dynamics.