Master Sgt. Steven Burns, 28th Medical Operations Squadron NCO in charge of immunizations, administers an influenza vaccination to Staff Sgt. Carl Amarr, 28th Maintenance Squadron aerospace craftsman, at Ellsworth Air Force Base, S.D., March 13, 2012. An annual influenza vaccine is the first and most important step in protecting against flu viruses. (U.S. Air Force photo by Airman 1st Class Zachary Hada/Released)