Vaccines (Jul 2025)

COVID-19 Vaccine Response in Allo-HSCT Recipients: Insights from a Real-World Prospective Cohort Study

  • Emine Merve Savaş,
  • Şeyma Yıldız,
  • Zübeyde Nur Özkurt,
  • Zehra Baltacı,
  • Özlem Güzel Tunçcan,
  • Zeynep Arzu Yeğin,
  • Kayhan Çağlar,
  • Nurdan Köktürk,
  • Gonca Erbaş,
  • Gülendam Bozdayı,
  • Münci Yağcı

DOI
https://doi.org/10.3390/vaccines13070726
Journal volume & issue
Vol. 13, no. 7
p. 726

Abstract

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Background: Allogeneic hematopoietic stem cell transplant (Allo-HSCT) recipients are still at increased risk of severe COVID-19 infection. Vaccination is a critical strategy to protect this population. This real-world prospective cohort study aimed to evaluate the immune response and clinical outcomes of COVID-19 vaccines in Allo-HSCT recipients. Methods: Allo-HSCT recipients (median age: 48 years) who received either the BNT162b2 or CoronaVac vaccines were included. Antibodies against the SARS-CoV-2 spike protein were quantitatively measured using the chemiluminescent microparticle immunoassay. Patient- and vaccine-related factors affecting antibody responses were analyzed. Adverse events, including graft-versus-host disease (GVHD) and post-vaccine infections, were recorded. Results: Among 95 Allo-HSCT recipients, 86.3% achieved adequate antibody responses following COVID-19 vaccination. Patients receiving ≥3 vaccine doses showed significantly higher antibody titers compared to those with only 2 doses (OR: 0.11; 95% CI: 0.02–0.53; p = 0.006 **). The use of Ruxolitinib or Ibrutinib was associate with increased odds of low antibody response (OR: 38.39; 95% CI: 3.14–468.95; p = 0.004 **). Hypogammaglobulinemia (low serum IgG levels) was associated with a reduced antibody response (OR: 0.17; 95% CI: 0.03–0.96; p = 0.045 *), while no significant correlation was found between serum IgA levels and antibody responses (p = 0.672). Three cases of post-vaccine GVHD were observed, and no fatalities related to COVID-19 occurred during the study. Conclusions: COVID-19 vaccination is safe and effective in Allo-HSCT recipients, with stronger responses especially following ≥3 vaccine doses. Patients receiving GVHD treatment or with hypogammaglobulinemia exhibited impaired responses, emphasizing the need for tailored vaccination strategies and close monitoring in this population.

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