BCG Vaccination May Impact HSCT Outcome

By Patrick Daly - Last Updated: December 22, 2022

In a recent study, researchers evaluated if administering the bacillus Calmette-Guérin (BCG) vaccine upon birth affected the outcomes of hematopoietic stem cell transplantation (HSCT) in pediatric patients with severe combined immunodeficiency (SCID). According to the study’s lead author, Amir Hamidieh, data showed early BCG vaccination was associated with an increased risk of acute graft-versus-host disease (aGVHD).

The study, published in Transplantation and Cellular Therapy, enrolled 30 patients with SCID who underwent HSCT with reduced intensity conditioning and were then followed for 2 years. Researchers compared HSCT outcomes between patients who were BCG-vaccinated (n=18) and those who were non-BCG-vaccinated (n=12).

BCG Vaccination at Birth May Increase aGVHD Risk

According to the authors, the data showed patients who had been vaccinated at birth exhibited higher incidences of aGVHD compared with those who had not been vaccinated. Comparatively, authors found the rate of chronic GVHD was similar between the 2 groups. Likewise, the rate of overall survival was similar between vaccinated and nonvaccinated patients.

In their report, the investigators theorized that the reduced intensity conditioning regimen could be the cause of the comparable survival outcomes in BCG-vaccinated patients despite the risks associated with vaccination, considering no other variation between the groups was present.

The authors acknowledged further studies are needed to validate their findings, but they also suggested “that the administration of BCG vaccine should be deferred until 3 months of age so that apt testing, without the interference of maternal antibodies, could be performed.”

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