Haemophilus influenzae type b vaccines: history, choice and comparisons.

The conjugate Haemophilus influenzae type b (Hib) vaccines are safe and far more immunogenic among infants and young children than is the unconjugated H. influenzae type b polysaccharide. The vaccines differ in their immunogenicity when used for primary immunization of infants, and these differences appear to be predictive of efficacy, such that some vaccines might be more suitable than others in certain populations.