Introduction: Patients after solid organ transplantation are at an increased risk for microbial infections. Due to therapeutic immunosuppression, the response to active immunizations may be reduced. The serological efficacy of pneumococcal and influenza vaccination was studied in heart transplant recipients.
Patients and methods: Sixteen patients over 1 year after heart transplantation and control patients were immunized with a 23-valent pneumococcal vaccine and a triple-split influenza vaccine. Pre- and postvaccinal antibody titers were serologically determined, including quantitation of specific antibodies against nine pneumococcal serotypes.
Results: Both vaccines were well tolerated without systemic reactions or infectious complications. Median postvaccinal pneumococcal antibody titers in the transplant patients were comparable to controls (5513 U/ml, range: 694-41007, vs. 5490 U/ml, range: 1088-38042; P=NS); vaccination was successful in 23/23 (100%) of controls and in 15/16 (94% plus 1 borderline positive case) of the transplant recipients. Specific antibody titers were similar for eight of nine serotypes; only the immune response against serotype 3 was reduced after transplantation. The efficacy of influenza vaccination was significantly impaired in transplant patients against all three virus strains (62% vs. 97%, P<0.01/50% vs. 94%, P<0.001/37% vs. 80%, P<0.01), but 9/16 (56%) of patients still showed a sufficient immune response to two out of three virus strains. No clinical or demographic predictors of successful vaccination could be established.
Conclusions: Pneumococcal vaccination under cyclosporine-based immunosuppression after heart transplantation is safe and equally effective as in healthy controls. In contrast, the immune response to influenza vaccination is significantly reduced, although not completely abolished. This differential response might be accounted for by T cell-independent antibody production against polysaccharide antigens contained in the pneumococcal vaccine.