He works at Thomas Jefferson University Hospital in Philadelphia.[1][2][3] Since 2007 he has been an assistant professor of otolaryngology at Thomas Jefferson University.[1][2] Since 2016 he has served as the Senior Director of Health Policy and Innovation at the Sidney Kimmel Cancer Center.[14][15] Krein is a founding partner and co-director of the hospital's Herbert Kean Center for Facial Aesthetics.[6]