Immunogenicity of Haemophilus influenzae type b conjugate vaccine in children with sickle cell disease.

OBJECTIVE--To determine the safety and immunogenicity of Haemophilus influenzae type b conjugate vaccine in children with sickle cell disease. RESEARCH DESIGN--Prospective, nonrandomized, nonblinded study. SETTING--Hospital-based, comprehensive sickle cell center. PATIENTS--Children with sickle cell disease aged 18 months to 18 years who were previously unvaccinated or had an inadequate or waning response to H influenzae type b polysaccharide vaccine. SELECTION PROCEDURES--Consecutive eligible patients. INTERVENTIONS--Vaccination and observation for adverse effects. Blood samples were taken before and 1 to 2 and 6 months after vaccination to measure anticapsular antibody levels. MEASUREMENTS AND RESULTS--Vaccination was well tolerated. One hundred percent and 96% of the 31 immunized children had postvaccination anticapsular antibody concentrations of greater than 0.15 and 1.0 mg/L, respectively. Six months after vaccination, 100% and 89% of children had these antibody concentrations. CONCLUSIONS--H influenzae type b conjugate vaccines are safe and highly immunogenic in children with sickle cell disease. It is likely that these vaccines will be protective against invasive H influenzae type b disease.