Haemophilus influenzae type B conjugate vaccines

OBJECTIVE: To review the epidemiology of Haemophilus influenzae type b (Hib) disease, the first Hib vaccine and its limitations, the characteristics and clinical efficacy of the newer conjugate vaccines, and the current recommendations for administration of Hib vaccines. DATA SOURCES: Pertinent literature was identified via a MEDLINE search. Additionally, references cited in published articles were used as data sources. STUDY SELECTION: Studies describing the epidemiology of Hib disease and the efficacy and/or immunogenicity of the Hib vaccines are reviewed. DATA SYNTHESIS: Serious invasive disease secondary to Hib infection causes significant morbidity and mortality in children between the ages of three months and five years. The original Hib vaccine was found to be ineffective in stimulating an adequate immune response in children younger than two years of age. The new Hib conjugate vaccines provide superior efficacy and immunogenicity compared with the original unconjugated vaccine. They stimulate an immune response that is distinctly different from that elicited by the original vaccine. Two vaccine products are currently licensed for use in children as young as two months of age, thus conferring immunity to those children at highest risk for Hib disease. CONCLUSIONS: The new Hib conjugate vaccines provide excellent efficacy and, when used as recommended, may significantly reduce the incidence of invasive Hib disease and its sequelae.