I was admitted to and have accepted an offer from Vanderbilt Health Policy.
For posterity's sake, here are my results and their dates:
Wisconsin Population Health Sciences PhD: Acceptance, January 5.
Johns Hopkins University Health Policy and Management PhD: Waitlist, February 9.
Michigan Health Services Organization and Policy PhD: Rejection, February 9.
Vanderbilt Health Policy PhD: Acceptance, February 21.
UNC Health Policy and Management PhD: No response.