SARS-CoV-2-reactive antibody detection after SARS-CoV-2 vaccination in hematopoietic stem cell transplant recipients: Prospective survey from the Spanish Hematopoietic Stem Cell Transplantation and Cell Therapy Group.

This is a multicenter prospective observational study which included a large cohort (n = 397) of allogeneic (allo-HSCT) (n = 311) and autologous (ASCT) hematopoietic stem cell transplant (n = 86) recipients who were monitored for antibody detection within 3 to 6 weeks after complete SARS-CoV-2 vaccination from February 1st 2021 to July 20th 2021. Most patients (n = 387, 97.4%) received mRNA-based vaccines. Most of recipients (93%) were vaccinated more than 1 year after transplant. Detectable SARS-CoV-2-reactive antibodies were observed in 242 (78%) of allo-HSCT and in 73 (85%) of ASCT recipients. Multivariate analysis in allo-HSCT recipients identified lymphopenia <1x109 /mL [Odds ratio (OR) 0.33, 95% confident interval (95% C.I.) 0.16-0.69, p = 0.003), active graft-vs-host disease (GvHD) (OR 0.51, 95% C.I. 0.27-0.98, p = 0.04) and vaccination within the first year of transplant (OR 0.3, 95% C.I. 0.15-0.9, p = 0.04) associated with lower antibody detection whereas. In ASCT, non-Hodgkin's lymphoma (NHL) (OR 0.09, 95% C.I. 0.02-0.44, p = 0.003) and active corticosteroid therapy (OR 0.2, 95% C.I. 0.02-0.87, p = 0.03) were associated with lower detection rate. We report an encouraging rate of SARS-CoV-2-reactive antibodies detection in these severe immunocompromised patients. Lymphopenia, GvHD, timing of vaccine and NHL and corticosteroids therapy should be considered in allo-HSCT and ASCT respectively, to identify candidates for SARS-CoV-2 monitoring. This article is protected by copyright. All rights reserved.