Deficiency of SARS-CoV-2 T-cell responses after vaccination in long-term allo-HSCT survivors translates into abated humoral immunity
Sigrun Einarsdottir, Anna Martner, J. Waldenström, Malin Nicklasson, Johan Ringlander, Mohammad Arabpour, Andreas Törnell, Hanna Grauers Wiktorin, Staffan Nilsson, Rudy Bittar, Malin S. Nilsson, Mikael Lisak, Malin Veje, Vanda Friman, Samer Al-Dury, Tomas Bergström, Per Ljungman, Mats Brune, Kristoffer Hellstrand, Martin Lagging
Abstract
Recipients of allogeneic hematopoietic stem cell transplantation (allo-HSCT) for hematological diseases are at risk of severe disease and death from COVID-19. To determine the safety and immunogenicity of BNT162b2 and mRNA-1273 COVID-19 vaccines, samples from 50 infection-naive allo-HSCT recipients (median, 92 months from transplantation, range, 7-340 months) and 39 healthy controls were analyzed for serum immunoglobulin G (IgG) against the receptor binding domain (RBD) within spike 1 (S1) of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2; anti-RBD-S1 IgG) and for SARS-CoV-2-specific T-cell immunity, reflected by induction of T-cell-derived interferon-γ in whole blood stimulated ex vivo with 15-mer SI-spanning peptides with 11 amino acid overlap S1-spanning peptides. The rate of seroconversion was not significantly lower in allo-transplanted patients than in controls with 24% (12/50) and 6% (3/50) of patients remaining seronegative after the first and second vaccination, respectively. However, 58% of transplanted patients lacked T-cell responses against S1 peptides after 1 vaccination compared with 19% of controls (odds ratio [OR] 0.17; P = .009, Fisher's exact test) with a similar trend after the second vaccination where 28% of patients were devoid of detectable specific T-cell immunity, compared with 6% of controls (OR 0.18; P = .02, Fisher's exact test). Importantly, lack of T-cell reactivity to S1 peptides after vaccination heralded substandard levels (<100 BAU/mL) of anti-RBD-S1 IgG 5 to 6 months after the second vaccine dose (OR 8.2; P = .007, Fisher's exact test). We conclude that although allo-HSCT recipients achieve serum anti-RBD-S1 IgG against SARS-CoV-2 after 2 vaccinations, a deficiency of SARS-CoV-2-specific T-cell immunity may subsequently translate into insufficient humoral responses.