Antibody Response to Pneumococcal Vaccine in Middle-aged and Elderly Patients Recently Treated for Pneumonia

Abstract

A substantial proportion of patients admitted to the hospital for pneumonia have been treated in a hospital during the preceding 4 to 5 years, and patients previously treated in a hospital for pneumonia seem to be at an especially high risk for another episode of pneumonia. Many cases of pneumococcal infection might therefore be prevented by immunizing admitted patients with pneumococcal vaccine at discharge or at follow-up. The aim of this study was to investigate the type-specific antibody response to pneumococcal vaccine in middle-aged and elderly patients at follow-up 8 weeks after hospital treatment for pneumonia. A total of 92 individuals, 50 to 85 years old, participated in the study. One group consisted of 65 individuals treated in the hospital for pneumonia 8 weeks before vaccination (mean age, 67 years), and another group consisted of 27 individuals who had not recently been treated for pneumonia (mean age, 67 years). All 92 individuals received a single dose of a 23-valent pneumococcal vaccine. The type-specific antibody responses to six pneumococcal capsular polysaccharide antigens included in the vaccine as well as antibodies against the 23-valent pneumococcal vaccine were measured before and 3 to 4 weeks after vaccination by use of an enzyme-linked immunosorbent assay. The antibody concentrations before and after vaccination were comparable in the two groups, as were antibody fold increases from prevaccination to postvaccination serum. No serious adverse events were recorded. Pneumococcal vaccination at follow-up 8 weeks after treatment in the hospital for pneumonia seems to elicit an adequate antibody response without notable adverse reactions.