Vaccine prevention of Haemophilus influenzae type b disease: past, present and future.

In little more than half a century we have come a long way toward the eventual elimination of invasive Hib disease as a major threat to children in the United States. The Haemophilus b polysaccharide vaccine has provided the first tool for large scale public health intervention efforts in specific target groups of children older than 18 months of age who are likely to benefit from immunization. Immunization programs using the currently available vaccine represent an interim measure that is likely to be replaced within the next few years by new programs utilizing an improved vaccine with greater potential for preventing invasive Hib disease in susceptible infants and young children. Prospects appear good that an improved second generation vaccine that will provide protective efficacy in infants during the first year of life will become available in the near future.