STUDIES ON PNEUMOCOCCUS-VACCINE ALONE OR MIXED WITH DTP AND ON PNEUMOCOCCUS TYPE 6B AND HAEMOPHILUS-INFLUENZAE TYPE-B CAPSULAR POLYSACCHARIDE-TETANUS TOXOID CONJUGATES IN 2-TO-5-YEAR-OLD CHILDREN WITH SICKLE-CELL-ANEMIA

Pneumococcus vaccine, injected alone or mixed with diphtheria-tetanus toxoid-pertussis, did not elicit significant concentrations of pneumococcus type 6 antibodies in 2− to 5-year-old sickle cell anemia patients (n = 22). Reinjection 5 months later failed to elicit a booster response to pneumococcus type 6. We then injected conjugates of pneumococcus type 6B and of Haemophilus influenzae type b (Hib), each bound to tetanus toxoid (TT), alternatively at monthly intervals into sickle cell anemia patients of the same age group (n = 25); most received 3 injections of each vaccine. Pneumococcus vaccine was administered to 19 patients and Hib to 1 at approximately 1 year of age. Blood samples were taken before each and approximately 6 months after the last injection. Infrequent and minimal local reactions and only 6 episodes of fever (3%) occurred after injection of the conjugates. Pneumococcus type 6B-TT elicited a rise in the geometric mean concentration of pneumococcus type 6 antibodies (Ab) from 104 ng of antibody nitrogen (AbN)/ml in preimmunization sera to 385 ng of AbN/ml after the first injection (P < 0.01). There were further increases after the 2 subsequent injections; 6 months after the third injection, the mean concentration was 940 ng of AbN/ml and 15 of 16 (94%) had > 300 ng of AbN/ml. Hib-TT elicited a 160-fold increase of Hib antibodies to a geometric mean concentration of 39.0 μg of Ab/ml after the first injection. These levels rose approximately 2-fold following 2 additional injections to 71.7 μg/ml and declined to 10.7 μg/ml at the 6-month sampling. All had > 0.15 μg of Hib Ab/ml (estimated protective level) after all injections. The patients received DTP during infancy and at 18 months of age; all had > 0.01 unit/ml of tetanus antitoxin (protective level) in their preimmunization sera. The mean antitoxin titer rose approximately 8-fold after the first injection (pnemococcus type 6B-TT), remained unchanged after the subsequent injections and declined to about 3-fold over the preimmunization levels at the 6-month blood sampling. © 1990 by Williams & Wilkins.