Attenuated humoral response against SARS-CoV-2 mRNA vaccination in allogeneic stem cell transplantation recipients

Cellular and humoral immunogenicity against SARS-CoV-2 vaccination or infection is associated with the memory phenotype of T- and B-lymphocytes in adult allogeneic hematopoietic cell transplant recipients

We conducted a cross-sectional study to evaluate cellular and humoral immunogenicity against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination or infection and examine how lymphocyte subpopulations in peripheral blood correlate with cellular and humoral immunogenicity in adult allogeneic hematopoietic cell transplantation (HCT) recipients. The median period from SARS-CoV-2 vaccination or infection to sample collection was 110.5 days (range, 6-345 days). The median SARS-CoV-2 spike-specific antibody level was 1761 binding antibody units (BAU)/ml (range, 0 to > 11,360 BAU/ml). Enzyme-linked immunosorbent spot (ELISpot) assay of T cells stimulated with SARS-CoV-2 spike antigens showed that interferon-gamma (IFN-γ)-, interleukin-2 (IL-2)-, and IFN-γ + IL-2-producing T cells were present in 68.9%, 62.0%, and 56.8% of patients, respectively. The antibody level was significantly correlated with frequency of IL-2-producing T cells (P = 0.001) and IFN-γ + IL-2-producing T cells (P = 0.006) but not IFN-γ-producing T cells (P = 0.970). Absolute counts of CD8+ and CD4+ central memory T cells were higher in both IL-2- and IFN-γ + IL-2-producing cellular responders compared with non-responders. These data suggest that cellular and humoral immunogenicity against SARS-CoV-2 vaccination or infection is associated with the memory phenotype of T cells and B cells in adult allogeneic HCT recipients.

Antibody response after third dose of COVID-19 mRNA vaccination in allogeneic hematopoietic stem cell transplant recipients is comparable to that in healthy counterparts

To determine the efficacy of SARS-CoV-2 mRNA vaccination for allogeneic hematopoietic stem cell transplantation (allo-HSCT) recipients, we measured antibody titer serially in 92 allo-HSCT patients. Among the evaluable 87 patients, median age at vaccination was 53 years (range, 18-75). The average time between allo-HSCT and vaccination was 3.3 years (range, 0.5-15.7). One month after the second dose, 70 patients (80.5%) had a positive response, whereas 17 patients (19.5%) had a negative response (< 20 U/mL). Only patients older than 44 years had a negative response. Low IgM level was the only significant predictor of vaccine failure in elderly patients. When antibody response before and after the third vaccination was examined in 47 patients, antibodies increased significantly from a median of 18.3 U/mL to 312.6 U/mL (P < 0.01). The median antibody titer after the third vaccination of healthy individuals (n = 203) was 426.4 U/mL, which was comparable to that of patients (P = 0.2). The antibody titer after the third mRNA vaccination increased even in patients whose first two mRNA vaccinations failed. These findings suggest that allo-HSCT recipients should receive the mRNA vaccine regularly.

Attenuated immunogenicity of SARS-CoV-2 vaccines and risk factors in stem cell transplant recipients: a meta-analysis

Immunogenicity of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination is diminished in hematopoietic stem cell transplant (HSCT) recipients. To summarize current evidence and identify risk factors for attenuated responses, 5 electronic databases were searched since database inceptions through 12 January 2023 for studies reporting humoral and/or cellular immunogenicity of SARS-CoV-2 vaccination in the HSCT population. Using descriptive statistics and random-effects models, extracted numbers of responders and pooled odds ratios (pORs) with 95% confidence intervals (CIs) for risk factors of negative immune responses were analyzed (PROSPERO: CRD42021277109). From 61 studies with 5906 HSCT recipients, after 1, 2, and 3 doses of messenger RNA (mRNA) SARS-CoV-2 vaccines, the mean antispike antibody seropositivity rates (95% CI) were 38% (19-62), 81% (77-84), and 80% (75-84); neutralizing antibody seropositivity rates were 52% (40-64), 71% (54-83), and 78% (61-89); and cellular immune response rates were 52% (39-64), 66% (51-79), and 72% (52-86). After 2 vaccine doses, risk factors (pOR; 95% CI) associated with antispike seronegativity were male recipients (0.63; 0.49-0.83), recent rituximab exposure (0.09; 0.03-0.21), haploidentical allografts (0.46; 0.22-0.95), <24 months from HSCT (0.25; 0.07-0.89), lymphopenia (0.18; 0.13-0.24), hypogammaglobulinemia (0.23; 0.10-0.55), concomitant chemotherapy (0.48; 0.29-0.78) and immunosuppression (0.18; 0.13-0.25). Complete remission of underlying hematologic malignancy (2.55; 1.05-6.17) and myeloablative conditioning (1.72; 1.30-2.28) compared with reduced-intensity conditioning were associated with antispike seropositivity. Ongoing immunosuppression (0.31; 0.10-0.99) was associated with poor cellular immunogenicity. In conclusion, attenuated humoral and cellular immune responses to mRNA SARS-CoV-2 vaccination are associated with several risk factors among HSCT recipients. Optimizing individualized vaccination and developing alternative COVID-19 prevention strategies are warranted.