1 From the Division of Geographic Medicine, Department of International Health, The Johns Hopkins University School of Hygiene and Public Health, Baltimore, Maryland, the Division of Infectious Disease of the Dana Farber Cancer Institute, Harvard University, and the Biologic Laboratories of the Massachusetts Center for Disease Control, Boston, Massachusetts
Haemophilus influenzae type b is the leading cause of meningitis in children younger than 5 years of age in the United States.1 The incidence of infection with H influenzae type b in certain populations, such as Apache and Navajo Indians and Alaskan Eskimos, is 10 to 20 times higher than in the general US population.2-4 Another important feature of H influenzae type b infections in these populations is that more than 80% of the cases occur during the first year of life, with 35% to 45% occurring during the first 6 months.
One of the currently licensed vaccines that contains the capsular polysaccharide of the H influenzae type b organism is not reliably immunogenic in infants younger than 18 months of age.5,6 A number of new H influenzae type b vaccines prepared by covalently coupling the H influenzae type b capsular polysaccharide with a protein carrier antigen are undergoing clinical evaluation.7-13 One of these conjugate vaccines was shown to be efficacious in preventing disease caused by H influenzae type b in Finnish infants when they were immunized at 3, 4, and 6 months of age.14 Unfortunately, in a recently concluded trial, the same vaccine was not found to be efficacious in preventing such disease in infants younger than 1 year of age among the Alaskan Eskimo population.15
We have evaluated an alternative approach for protecting high-risk infants. A human hyperimmune globulin called bacterial polysaccharide immune globulin (BPIG) was prepared from the pooled plasma of adult blood donors immunized with H influenzae type b, pneumococcal, and meningococcal capsular polysaccharide.16