Immunization of children with sickle cell disease with Haemophilus influenzae type b polysaccharide vaccine.

There are limited data concerning safety and immunogenicity of Haemophilus influenzae type b polysaccharide vaccine in children with sickle cell disease. Ninety-eight patients with sickle cell disease (65 with SS phenotype, 23 with SC phenotype, and 10 with S beta-thalassemia) 1.5 to 20 years of age were given 25 micrograms of vaccine subcutaneously. The vaccine was well tolerated; mild side effects were observed in 6 of 98 (6.1%) children. In addition, one patient with a recent vasoocclusive crisis was hospitalized because of fever and vasoocclusive crisis 8 hours after vaccination. Prevaccination anticapsular antibody concentrations (by radioimmunoassay) were less than 0.15 microgram/mL in 7 of 11 children 18 to 24 months of age (geometric mean 0.17 microgram/mL), in 10 of 25 children 2 to 5 years of age (geometric mean 0.36 microgram/mL), and in 3 of 50 patients 6 to 20 years of age (geometric mean 1.03 microgram/mL). Inadequate response (1- to 2-month postvaccination antibody level less than 1 microgram/mL) was found in 3 of 5 children 18 to 24 months of age (geometric mean 1.74 microgram/mL), in 8 of 21 children 2 to 5 years of age (geometric mean 2.20 micrograms/mL), and in 2 of 49 patients 6 to 20 years of age (geometric mean 18.03 micrograms/mL). Six months after vaccination, greater than 1 microgram/mL of antibody was present in the 2 children 6 to 20 years of age with inadequate response but not in the 7 children 2 to 5 years of age with inadequate response.(ABSTRACT TRUNCATED AT 250 WORDS)