Status of immunity for vaccine--preventable diseases in children after hematopoietic stem cells transplantation

Abstract

Introduction: patients treated with hematopoietic stem cell transplantation (HSCT) lose immune memory accumulated through a lifetime. They are at increased risk of developing infections with microorganisms such as Haemophilus influenza, Streptococcus pneumoniae and others for which vaccines are available. Therefore, all patients after HSCT should be routinely revaccinated. Systemic reimmunization after HSCT is a relatively neglected area especially in countries which have not national recommendations and there is lack of systemic regulations in health care system.

Objective: the rate of immunization before transplantation and the persistence of vaccine-specific antibodies after HSCT was assessed.

Study design: a group of38 children after stem cell transplantation (19 autologous, 19 allogeneic) was studied.

Results: only a few patients completed standard vaccination protocol before HSCT. At the median time of 29 (range: 6-67) months after autologous and 13 (range: 8-33) months after allogeneic HSCT, when the revaccination was commenced, the majority of children had concentration of antibody lower than the minimum protective thresholds. That was 82% for tetanus, 71% for Hib and varicella, 46% for HBV and 38% for diphtheria.

Conclusions: all HSCT recipients should be routinely revaccinated to stimulate the immunity to the vaccine-preventable diseases.