Current status of pneumococcal polysaccharide immunization in patients with sickle cell disease or impaired splenic function.

It is now possible to prevent effectively the occurrence of overwhelming pneumococcal infection from the majority of pneumococcal organisms in patients with increased susceptibility to infection. Immunization of patients with sickle cell disease and patients with splenectomy results in a significant increase in antibody amounts which persist for long periods of time. Patients under 2 years of age and patients with Hodgkin's disease and splenectomy respond less well. Most "vaccine failures" which have been described, have been in immunosuppressed patients, or a result of infection with S. pneumoniae type 6A. Future directions in the development of a more effective vaccine for patients under 2 years of age and immunosuppressed patients will include research efforts to formulate a new immunogenic vaccine. Definitive recommendations regarding booster immunization must await more definitive studies, but current data suggests that booster immunization is not necessary for at least 5-6 years following primary immunization.