U.S. Air Force Staff Sgt. Justin Pribble, 31st Medical Operations Squadron allergy and immunizations NCO in charge, administers an influenza vaccine to a patient, Oct. 14, 2015, at Aviano Air Base, Italy. The vaccination is required for uniformed personnel and civilian healthcare employees working in patient care to help prevent influenza. (U.S. Air Force photo by Senior Airman Areca T. Bell/Released)