Asplenic persons are at increased risk of overwhelming sepsis caused by Streptococcus pneumoniae. Vaccination with polyvalent pneumococcal polysaccharide has been shown to stimulate a nearly normal antibody response in these individuals, indicating that active vaccination might prevent pneumococcal disease in this population. To obtain information on the duration of protective levels of pneumococcal antibody, 33 asplenic children were vaccinated and antibody levels were measured at intervals for up to 4 1/2 years after vaccination. Significant antibody decline was observed in children who had undergone splenectomy because of trauma, but antibody decline was not observed in children whose spleens had been removed because of hereditary spherocytosis. There was a highly significant difference in rates of antibody decline among the 12 antibody serotypes measured: types 1, 4, 6A, 7F, 8, 19F, and 23F showed the greatest decline. Based on measured rates of antibody decline, subprotective antibody levels (antibody nitrogen <300 ng/ml) for types 7F, 8, and 19F would be reached 1 to 2 years after vaccination; type 6A never reached the protective level; and antibodies against the remaining eight types either were within the protective range initially or did not show significant decline. Asplenic children may benefit from revaccination with certain antigen types (7F, 8, and 19F) 1 to 2 years after initial vaccination.
Bibliographical noteFunding Information:
From the Department of Pediatrics, University of Minnesota Medical School; the Division of Biometry, University of Minnesota School of Public Health; and the Department of Microbiology, Downstate Medical Center. Supported in part by contract AI-42541 from the National Institute of Allergy and Infectious Diseases. Submitted for publication Dec. 27, 1983; accepted April 20, 1984. Reprint requests: G. Scott Giebink, M.D., Department of Pediatrics, University of Minnesota, Box 483 Mayo Memorial Building, 420 Delaware St. SE, Minneapolis, MN 55455.
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