Immunogenecity of Early Post Transplant Vaccination in Children

Background:  Vaccine-preventable diseases continue to pose a risk to HSCT recipients, thus guidelines recommend routine vaccination after HSCT.  Pediatric data is limited regarding vaccine immunogenicity post-HSCT and may contribute to inconsistent vaccination practices.

Objective: Prospective, observational study to determine the immunogenicity of hepatitis B, tetanus, and pneumococcal vaccination in children after HSCT. Secondary objective was to evaluate correlation with T&B cell numbers.

Patients and Methods: Children receiving a HSCT from January 2010 thru October 2012 were prospectively followed.  Three doses of Hepatitis, PCV 13, and Pentacel were given per guidelines two months apart.  Pre and post vaccine-specific antibodies and T&B cell studies were performed at 6 and 12 months post-HSCT.

Results:  Compliance with current vaccine recommendations occurred in 15 of 33 (45 %) subjects. Of the 15 subjects, 12 were evaluable receiving vaccinations and lab draws according to the predefined schedule. Patient characteristics are described in Table 1.

Time to immunization post HSCT was a median of 197 days [180-404].  2/12 subjects were chronic GVHD patients on immunosuppression at the time of re-vaccination. One of these patients did not respond to vaccination. Protective antibody levels were found for tetanus in 83% of subjects (median of 2.6 IU/mL [range 0.1-7]) and 69% of patients for hepatitis.   4 evaluable subjects responded to at least 1 pneumococcal serotype, 2 of 4 (50%) to at least 6 serotypes; 3, 4, 6B, and 19F were most immunogenic.  There was no correlation between total peripheral WBC or CD3, CD8, CD19 numbers and tetanus antibody concentrations.

Conclusions: Despite the small sample size in our cohort, hepatitis, tetanus, and pneumococcal vaccination was immunogenic in a majority of subjects when given 6 months post HSCT. Pneumococcal serotypes cited to cause invasive disease post HSCT were most immunogenic, but additional data is needed.

Table 1. Patient Characteristics

Male                                                     8 (62%)

Age at transplant                             7.8 (0.6-18.9)

Transplant Type

   Allogeneic                                        11 (85%)

   Autologous                                      2   (15%)

Donor Source

   Bone marrow                                 7 (54%)

   Peripheral blood                           3 (23%)

   Umbilical cord blood                    3 (23%)

Preparative Regimen

  Myeloablative                                 10 (77%)

     Serotherapy                                     6 (60%)

  Non-myeloblative                           3 (23%)

      Serotherapy                                  2 (67%)

GVHD Prophylaxis

    CNI/MTX                                         6 (60%)

    CNI/MMF                                        4 (40%)