Pneumococcal vaccine: clinical efficacy and effectiveness.

Streptococcus pneumoniae causes substantial morbidity and mortality. Incidence and severity are increased among populations with some chronic diseases. The currently available polyvalent polysaccharide vaccine induces antibody production among immunologically competent recipients against the 14 serotypes responsible for 80% of pneumococcal bacteremia in the efficacious in clinical trials with healthy young men in epidemic conditions and in patient with sickle cell anemia. Similar trials in two other high-risk populations had inconclusive results. Decisions on vaccine use now largely rest on indirect evidence of efficacy derived from knowledge of disease incidence, severity, and antibody response to vaccination among patient groups. Findings of a literature review suggest vaccinating high-risk patients immunologically competent to produce homotypic antibodies in response to vaccination with polysaccharide antigen, while continuing investigation of disease incidence, severity, serotype distribution, and immunologic response among high-risk groups and postmarketing surveillance efforts among all vaccinated patients.