Haemophilus influenzae disease and immunization in developing countries.

Haemophilus influenzae is one of the leading causes of severe bacterial infection in children of developing regions, causing 30% of the cases of culture-positive pneumonia and 20%-60% of the cases of bacterial meningitis. In infants and children, the majority of isolates from cerebrospinal fluid and blood and 16%-38% of pulmonary isolates are H. influenzae type b. The availability of several new polysaccharide-protein conjugate vaccines for the prevention of invasive disease due to H. influenzae type b prompts this review of the epidemiology of H. influenzae disease in the developing world and of the characteristics of current H. influenzae type b vaccines. To develop a strategy for use of H. influenzae type b vaccines in developing countries, the following data are needed: the age-specific attack rates of H. influenzae type b disease and the immunogenicity and efficacy of these vaccines in young infants in developing countries. Should H. influenzae type b vaccines prove to be inadequate for the prevention of H. influenzae pneumonia, the use of non-type b H. influenzae vaccines may be necessary.