The Centers for Disease Control and Prevention has called vaccines one of the “ten great public health achievements” of the 20th century.1 Indeed they are! During the medical career of the most senior of us (F.P.R.), the common occurrence of meningitis due to Hemophilus influenzae type b and the frightening disease of epiglottis has all but disappeared from our hospital wards. Varicella is becoming increasingly uncommon and only the most senior members of our faculty have regularly seen measles or mumps. What was once a simple schedule of vaccination for infants and children has become an almost impossible-to-remember table that requires updating annually, if not more often.