Thanks to vaccines, most U.S. children are protected against serious diseases such as measles, mumps, diphtheria, polio, and chickenpox. But what happens to that protection in adolescence? A teen who missed a vaccination or booster as a child may need to be immunized. Sometimes a teen's living situation or medical condition makes it necessary to get a vaccination. Other vaccines lose their protective power over time, and teens and young adults need a booster to stay protected. Learn more about which immunizations teens need by taking this quiz, based on information from the CDC.