Capt. Elvira Castillo, 433rd Aerospace Medicine Squadron, injects Senior Airman Isaac Arriaga with a flu vaccine during the 433rd Airlift Wing's Unit Training Assembly on Oct. 4, 2014 at Joint Base San Antonio-Lackland, Texas. The medics also passed out complimentary hand sanitizer and reminded wing members about hygiene as the nation enter the flu season. (U.S. Air Force photo by Tech Sgt. Carlos J. Trevino)