Q. We do not see many of the diseases vaccines prevent, so why do we still need vaccines?
A. Even though the incidence of diseases that vaccines prevent has been dramatically reduced or eliminated, vaccines are still needed for a few reasons.
- Some diseases, like pertussis, varicella and pneumococcus are common in the U.S.
- Diseases like measles, mumps, and Haemophilus influenzae type b (Hib) occur at low levels, but will quickly reappear if immunization rates drop even a little bit as illustrated by the 2015 measles outbreak in California.
- Diseases like polio and diphtheria have been eliminated from the U.S.; however, they are still common in other parts of the world. Because international travel is so common, these diseases are literally only a plane ride away.