Abstract
BACKGROUND: Sickle cell disease (SCD) can be cured by hematopoietic cell transplantation (HCT), but patients face increased risk of hepatitis B virus (HBV) reactivation due to immunosuppression. Understanding hepatitis B surface antibody (anti-HBs) kinetics is essential for optimizing HBV revaccination and posttransplant care. METHODS: This post hoc analysis examined HBV immunity, reactivation, and revaccination response in 71 SCD patients who underwent HCT at the National Heart, Lung, and Blood Institute (2008-2021) using alemtuzumab and low-dose total body irradiation. RESULTS: At baseline, 55% showed HBV immunity (anti-HBs ≥ 12 mIU/mL). Most patients responded to revaccination regardless of baseline immunity. Post-HCT revaccination was given to 93%, with 89% completing full series (Heplisav-B or Engerix-B). Vaccinated patients had a 67.5% chance of increased anti-HBs titers between Years 1 and 2, though no significant difference was seen compared to unvaccinated patients (p = 0.12). No HBV reactivation occurred; two patients with baseline HBcAb and HBsAg positivity showed decreasing HBV DNA levels. CONCLUSIONS: Results indicate that HBV immunity can decline post-HCT, but most patients remain immune, and revaccination is effective. However, some non-responders-especially those treated with IVIG, rituximab, or prolonged immunosuppression-need further study. Prospective research is needed to optimize revaccination timing and immune monitoring in this high-risk group.