Dr. Warren specializes in clinical research in Hospital Epidemiology and Infection Prevention, with a special focus on the epidemiology and prevention of device-related infections and surgical site infections, plus improving diagnostic stewardship of microbiological testing to accurately diagnose infectious diseases. Other areas of particular interest include bloodstream infections and S. aureus infection and colonization. He regularly attends on the Orthopedic Infectious Diseases Inpatient Consultation Service.

He has a long history of mentoring fellows within the Infectious Disease Division. The fellows he has mentored have gone into careers in academia, with faculty positions at Washington University, University of Illinois, SUNY-Stoneybrook, Catholic University of Chile, and Tokyo Metropolitan Tama Medical Center; public health, including the Centers for Disease Control and Prevention, plus state and city health departments; and private practice. He has also mentored Master of Public Health students. His mentees have published numerous first-author, peer-reviewed original manuscripts.