Vaccines are the single best thing that parents can do to protect their child and insure good health.  The viruses and bacteria that cause vaccine-preventable disease and death still exist. They have not disappeared. Vaccines have dramatically reduced the number of people who get infectious diseases and the complications these diseases produce. Without vaccines, epidemics of vaccine-preventable diseases would return, resulting in increased illness, disability, and death. Vaccine-preventable diseases also have a costly impact, resulting in doctor's visits, hospitalizations, and lost time from work for many parents.