Revaccination with measles, tetanus, poliovirus, Haemophilus influenzae type B, meningococcus C, and pneumococcus vaccines in children after hematopoietic stem cell transplantation

Background. There is a decrease in antibody levels after hematopoietic stem cell transplant (HSCT), and such patients may be at increased risk of acquiring vaccine-preventable infection. A simple and validated revaccination schedule is required. The aim of this study was to evaluate the immunogenicity of a revaccination schedule for pediatric HSCT recipients. Methods. Thirty-eight children (age, 1 - 18 years) who had undergone autologous or allogeneic HSCT for malignant diseases were recruited. All children received vaccinations in accordance with a predefined schedule. Antibody concentrations were measured before and 2 - 4 weeks after vaccination against tetanus; Haemophilus influenzae type b (Hib); meningococcus C; measles; poliovirus serotypes 1, 2, and 3; and 9 pneumococcus serotypes. Results. Before vaccination, protective antibody levels were found for tetanus in 95% of patients (geometric mean concentration [GMC], 0.07 IU/mL; 95% CI, 0.05 - 0.1 IU/mL), for Hib in 63% (GMC, 0.34 mu g/mL; 95% CI, 0.21 - 0.57 mu g/mL), for measles in 60% (GMC, 102 mIU/mL; 95% CI, 41 - 253 mIU/mL), for meningococcus C in 11% (geometric mean titer [GMT], 1: 4; 95% CI, 1: 2 - 1: 8.4), for all 3 poliovirus serotypes in 29%, and for all 9 pneumococcal serotypes in 0%. Vaccination resulted in a significant increase (P <= .05) in antibody levels to each vaccine antigen studied, with 100% of patients achieving protection against tetanus (GMC, 2.2 IU/mL; 95% CI, 1.8 - 2.7 IU/mL), 100% achieving protection against Hib (GMC, 8.4 mu g/mL; 95% CI, 7.6 - 9.3 mu g/mL), 100% achieving protection against measles (GMC, 2435 mIU/mL; 95% CI, 1724 - 3439 mIU/mL), 100% achieving protection against meningococcus C (GMT, 1: 5706; 95% CI, 1: 3510 - 1: 9272), 92% achieving protection against the 3 poliovirus serotypes, and >= 80% achieving protection against each of the heptavalent pneumococcal conjugate vaccine - associated serotypes. No factors relevant to age, underlying disease, or treatment type were found to significantly influence responses. Conclusion. Revaccination of pediatric HSCT recipients in accordance with this revaccination schedule provides a high level of protection against these vaccine-preventable diseases.