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Allogeneic haematopoietic stem cell transplant (HSCT) recipients remain at high risk of adverse outcomes from coronavirus disease 2019 (COVID-19) and emerging variants. The optimal prophylactic vaccine strategy for this cohort is not defined. T cell-mediated immunity is a critical component of graft-versus-tumour effect and in determining vaccine immunogenicity. Using validated anti-spike (S) immunoglobulin G (IgG) and S-specific interferon-gamma enzyme-linked immunospot (IFNγ-ELIspot) assays we analysed response to a two-dose vaccination schedule (either BNT162b2 or ChAdOx1) in 33 HSCT recipients at ≤2 years from transplant, alongside vaccine-matched healthy controls (HCs). After two vaccines, infection-naïve HSCT recipients had a significantly lower rate of seroconversion compared to infection-naïve HCs (25/32 HSCT vs. 39/39 HCs no responders) and had lower S-specific T-cell responses. The HSCT recipients who received BNT162b2 had a higher rate of seroconversion compared to ChAdOx1 (89% vs. 74%) and significantly higher anti-S IgG titres (p = 0.022). S-specific T-cell responses were seen after one vaccine in HCs and HSCT recipients. However, two vaccines enhanced S-specific T-cell responses in HCs but not in the majority of HSCT recipients. These data demonstrate limited immunogenicity of two-dose vaccination strategies in HSCT recipients, bolstering evidence of the need for additional boosters and/or alternative prophylactic measures in this group.

Original publication

DOI

10.1111/bjh.18312

Type

Journal article

Journal

Br J Haematol

Publication Date

08/2022

Volume

198

Pages

668 - 679

Keywords

BNT162b2, ChAdOx1, T-cell response, allogeneic bone marrow transplant, coronavirus disease 2019 (COVID-19), haematopoietic stem cell transplant (HSCT), severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), vaccines, Age Factors, Antibodies, Viral, BNT162 Vaccine, Bone Marrow Transplantation, COVID-19, COVID-19 Vaccines, ChAdOx1 nCoV-19, Hematopoietic Stem Cell Transplantation, Humans, Immunity, Cellular, Immunity, Humoral, Immunoglobulin G, Seroconversion, Transplantation, Homologous, Vaccination