U.S. Air Force Staff Sgt. Mario Hartaway, 633rd Medial Operations Squadron aerospace medicine technician, administers a flu shot to U.S. Army Col. Reggie Austin, 633rd Air Base Wing vice commander, at Langley Air Force Base, Va., Sept. 22, 2011. The most effective way to prevent the majority of flu infections is through an annual vaccination combined with proper hand washing and cough etiquette. (U.S. Air Force photo by Airman 1st Class Teresa Cleveland/Released)