Joint Base Langley-Eustis Airmen check-in at a triage table during a mass prophylaxis exercise at Langley Air Force Base, Va., Nov. 17, 2011. The 633rd Medical Group is responsible for the prophylaxis, or disease mitigation and containment measures, for the entire base populace of approximately 32,000 personnel within 48 hours of contamination (U.S. Air Force photo by Staff Sgt. Jeff Nevison)