Donor immunization with pneumococcal conjugate vaccine and early protective antibody responses following allogeneic hematopoietic cell transplantation

Patients undergoing hematopoietic cell transplantation (HCT) are at increased risk for infections with Streptococcus pneumoniaeand have long-lasting, impaired antibody responses to pneumococcal polysaccharide vaccines. We examined whether donor immunization with a heptavalent pneumococcal conjugate vaccine (PCV7) would elicit protective antibody responses to additional doses of vaccine administered early after transplantation. Ninety-six patients scheduled to receive an allogeneic hematopoietic cell transplant were randomized with their donors to receive either a dose of PCV7 vaccine or no vaccine before transplantation. All patients received PCV7 at 3 months, 6 months, and 12 months following transplantation, and serotype-specific antibody concentrations were determined after each dose. Following HCT,geometric mean antibody concentrations of patients in the immunized donor group were significantly higher for 5 of the 7 vaccine serotypes after one dose (P < .05) and for 4 of the 7 serotypes after 2 doses of vaccine (P < .03). Sixty-seven percent of patients in the immunized donor group had presumed protective IgG concentrations more than or equal to 0.50 μg/mL to all 7 serotypes following the first dose of vaccine compared to 36% in the unimmunized donor group (P = .05). After the third dose of vaccine, both groups had more than 60% of patients with concentrations at least 0.50 μg/mL to all vaccine serotypes. Donor immunization enhances early antibody responses of patients undergoing HCT to pneumococcal conjugate vaccine. A 3-dose schedule of PCV7 vaccine at 3, 6, and 12 months is immunogenic in these patients regardless of donor immunization.