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The Effect of Early BCG-Vaccination of SCID Pediatric Patients on the Outcome of Hematopoietic Stem Cell Transplantation Using Reduced Conditioning Regimen
Hamidieh, A. A., Jafari, L., Behfar, M., Karamlou, Y., Shamsipour, M., Mohseni, R., Farajifard, H., Salajegheh, P.
Transplantation and cellular therapy. 2022
Abstract
BACKGROUND The eminence of Bacillus Calmette-Guerin (BCG) vaccine in the vaccination program of newborns, especially in low-income developing countries where tuberculosis is prevalent, has been conspicuous throughout the years; however, the application of the aforementioned vaccine is not without constraints, especially in patients afflicted with immunodeficiency diseases, such as Severe Combined Immunodeficiency (SCID). OBJECTIVE The desideratum of this study is to evaluate whether or not the administration of BCG vaccine upon birth could attenuate the success of hematopoietic stem cell transplantation (HSCT) in SCID pediatric patients STUDY DESIGN In the current study, 30 SCID patients who underwent HSCT using reduced intensity conditioning regimen (RIC) were followed-up for 2 years post-HSCT. The outcome of HSCT was evaluated in both non-BCG-vaccinated (12 patients) and BCG-vaccinated (18 patients) groups. RESULTS Our results demonstrated that patients who had been BCG vaccinated displayed higher incidences of acute GvHD (aGvHD); however, the incidence of chronic GvHD did not differ between the two groups. The overall survival (OS) rate in patients who received the BCG vaccine was similar than their non-vaccinated counterparts. We speculate that the reason that BCG-vaccinated individuals' survival rate, despite having the risk factor of being BGC-vaccinated, was similar to the non-BCG-vaccinated group was due to the fact that they received RIC as their conditioning regimen. CONCLUSION The result of our study indicated that early BCG vaccination was associated with a higher risk of aGVHD. Additionally, the OS of BCG-vaccinated patients was similar in comparison to their non-vaccinated counterparts; alluding to the possibility that the same RIC regimen might be the reason for such outcome, since no other variation between the two groups existed. Regarding to the BCG vaccine affect the outcome of HSCT, we suggest that the administration of BCG vaccine should be deferred until three months of age so that apt testing, without the interference of maternal antibodies, could be performed; however, it is noteworthy that this study could benefit from a bigger cohort in order to further validate the outcome, as the possible reason for some factors not becoming statistically significant was the small sample size of this study.