Pneumococcal infections in children with sickle cell disease: increased incidence, immunological defects, vaccine failure, and prospects for the future.

There has been an increased incidence of pneumococcal infections in patients with sickle cell disease. Two immunological defects, functional asplenia and decreased pneumococcal serum opsonins due to a defect in the alternate pathway, have been shown to have a causal relationship to this increased incidence. The pneumococcal vaccine has been tried in children with sickle cell disease and failures have been reported in the literature. Clinical trials are now underway to determine the best method to prevent pneumococcal infections in children with sickle cell disease, that is by use of a vaccine, penicillin, or both.