flu vaccine shot_credit US Army Corps of Engineers Carol E. Davis

A medical technician with the Wiesbaden Army Health Clinic prepares a vaccine shot. Photo by Carol E. Davis courtesy of U.S. Army Corps of Engineers.

A medical technician prepares a flu vaccine injection. Credit: Courtesy / Carol E. Davis, U.S. Army Corps of Engineers

A medical technician with the Wiesbaden Army Health Clinic prepares an influenza shot for U.S. Army Corps of Engineers Europe District employees Oct. 19, 2011 at the Amelia Earhart Center. The Center for Disease Control recommends that everyone receive an annual flu vaccine, especially people in high-risk groups such as adults over 50 years old or older, anyone with asthma, and expectant mothers. Flu protection, from the shot, can take up to two weeks to develop and lasts for about one year. (U.S. Army Corps of Engineers photo by Carol E. Davis)