Immunogenicity and safety of the BNT162b2 mRNA COVID-19 vaccine in haematopoietic stem cell transplantation recipients

Abstract

The immunogenicity and safety of Pfizer-BioNTech BNT162b2 mRNA vaccine in allogeneic haematopoietic stem cell transplantation (HSCT) recipients are unknown. We prospectively followed 152 HSCT recipients who were at least six months following transplantation and with no active acute graft-versus-host disease (GVHD). Blood samples were taken 2-4 weeks after the second vaccination and analyzed for receptor-binding domain (RBD) antibodies and neutralizing antibodies (NA). 272 immunocompetent healthcare workers served as controls. At a median of 28 days after the second vaccination, 118 patients (77·6%) developed RBD immunoglobulin G (IgG) with a geometric mean titre (GMT) of 2·61 [95% CI (confidence interval), 2·16-3·16]. In the control group 269/272 (98·9%) developed RBD IgG, with a GMT of 5·98 (95% CI 5·70-6·28), P < 0·0001. The GMT of NA in HSCT recipients and controls was 116·0 (95% CI 76·5-175·9), and 427·9 (95% CI 354·3-516·7) respectively (P < 0001). Multivariate logistic regression analysis revealed that HSCT recipients with no chronic GVHD and no immunosuppressive therapy at the time of vaccination had significantly higher levels of NA following the second vaccination. Adverse events were minimal and were less common than in healthy controls. In conclusion; the BNT162b2 mRNA vaccination is safe and effective in HSCT recipients, especially those who are immunosuppression-free. A significant fraction developed protecting NA.

Keywords: COVID-19; haematopoietic stem cell transplantation; neutralizing antibodies; vaccination.

Fig 1

Quantitation of IgG following the second dose of the BNT162b2 vaccine in HSCT recipients and immunocompetent healthcare worker controls. (A) RBD IgG Levels, GMT B) Neutralizing antibodies above the cut‐off. C) Violin plot demonstrating the median RBD IgG titres among HSCT recipients and controls. The dotted black line indicates the limit level of positive antibodies. The short black line indicates GMT and 95% CI. GMT, geometric mean titres; HSCT, haematopoietic stem cell transplantation; RBD, receptor binding domain; S/CO, sample/cut‐off ratio. [Colour figure can be viewed at wileyonlinelibrary.com]

Fig 2

Correlation between RBD IgG and log‐transformed neutralizing antibodies. The correlation was analyzed two‐four weeks following the second vaccination, using Spearman's correlation by two‐tailed parametric t‐test means with a 95% CI. CI, confidence interval; IgG, immunoglobulin; RBD, receptor‐binding domain.