Evaluation of characteristics and post-vaccination status of 0-18 years old pediatric patients undergoing allogeneic hematopoietic stem cell transplantation

Re-vaccination program is necessary because of the loss of immunity to vaccine-preventable diseases after hematopoietic stem cell transplantation (HSCT). Administration of inactive and live vaccines in the program are recommended at 6 and 24 months after the transplant, respectively.The aim of this study was to evaluate the compliance of children with allogeneic HSCT to vaccination program and humoral immunity status after vaccination. Transplant records, vaccine records, and post-vaccination hepatitisB, hepatitisA, pertussis, measles, rubella, mumps, and varicella IgG antibody results of the children, who were completed their second year after allogeneic HSCT were evaluated. Median age of 173 patients was 70.5 months, 60.2% were males. Median re-vaccination onset time was 15 months, and it was delayed in patients diagnosed with graft versus host disease. Non-compliance to re-vaccination program was 70% for inactive vaccines and 86% for live vaccines. Oral polio was given to 22 of the patients, and Bacillus Calmette-Guerin vaccine was applied to three. Seropositivity rates of complete vaccinated patients were; 90.5% for Hepatitis B, 93.7% for hepatitis A, 91.2% for pertussis, 87.5% for measles, 91.3% for rubella, 79.2% for mumps, and 80% for varicella. Measles vaccine seropositivity was lower in the hemoglobinopathies group. Adenylate cyclase toxin antibody positivity rate was higher in patients vaccinated with low antigen-containing pertussis vaccine(Tdab) than high antigen(DaBT). Our findings reveal the necessity of conducting extensive multidisciplinary researches, improving vaccine adherence and the current practices. Promoting the Social Pediatrics Education at universities and performing preventive health services, such as child health monitoring and vaccination of special groups, by experienced experts may prevent negative consequences. Key words: Hematopoietic stem cell transplantation; revaccination; antibody; measles; pertussis