Characteristics of the 117 allogeneic HSCT recipients retained (median [range] age, 57 [20-75] years; 70 men [60%]) are provided in the Table. clinical history of COVID-19 and no active graft-vs-host disease more than 3 months after transplant. HSPA1 Vaccination was performed in our department between January 20 and April 17, 2021. All participants provided written informed consent, and the study was approved by Nantes University or college Hospital review R-121919 table. All procedures followed were in accordance with the ethical requirements of the responsible committee on human experimentation (institutional and national) and with the Helsinki Declaration of 1975, as revised in 2008. Previous asymptomatic COVID-19 contamination was investigated before the first vaccine injection by screening for antinucleocapsid antibodies (antiCSARS-CoV-2 immunoassay; Roche Elecsys). Antibody responses to the SARS-CoV-2 spike protein receptorCbinding domain name (Elecsys antiCSARS-CoV-2-S) were tested twice, at the time of the second injection and approximately 1 month after the second injection. As recommended by the manufacturer, titers greater than or equal to 0.8 U/mL were considered positive, with the highest value being greater than 250 U/mL. Associations between clinical characteristics and antibody responses were investigated using 1-sided 2 and Wilcoxon assessments with R statistical software version 4.0.2 (R R-121919 Project for Statistical Computing) via BiostaTGV. .05 was considered significant. Results Previous asymptomatic SARS-CoV-2 contamination was documented in 4 of 121 enrolled patients, who were, therefore, excluded from the study. They were vaccinated twice, and all reached specific IgG titers greater than 250 U/mL after the second dose. Characteristics of the 117 allogeneic HSCT recipients retained (median [range] age, 57 [20-75] years; 70 men [60%]) are provided in the Table. The median (range) interval between the first and the second dose was 22 (16-37) days. At the time of the second injection, 63 patients (54%) experienced a positive anti-spike antibody response. The median IgG titer for responders was 15.8 U/mL and ranged from 0.9 U/mL to more than 250 U/mL, with the latter occurring in 4 patients (3%). The second antibody screening was performed at a median (range) interval of 35 (18-77) days after the second dose and was positive in 97 patients (83%), with IgG titers ranging from 0.9 U/mL to greater than 250 U/mL; 72 (62%) patients reached the highest IgG titer. Factors associated with the absence of response were a haplotransplant, recent ( 1 year) HSCT (Physique), lymphopenia ( 1000?cells/L; to convert lymphocyte count to cells ?109/L, multiply by 0.001), and receipt of immunosuppressive treatment or chemotherapy at the time of vaccination (Table). Table. Patient Characteristics R-121919 and Results of Serological Assessments After Dose 1 and Dose 2 valuevaluevalue compares genoidentical, matched unrelated, and haploidentical donors. dRefers to corticosteroids used alone or in combination (ruxolitinib, cyclosporin A, and mycophenolate mofetyl). Open in a separate window Physique. AntiCSARS-CoV-2 Titers After the First and Second Vaccine InjectionsBox plots show antiCSARS-CoV-2 spike protein receptor titers after the first and the second vaccine injections. Lines within boxes denote medians, error bars denote 95% CIs, circles denote data for individual patients. Comparisons are between patients for whom follow-up after allogeneic hematopoietic stem cell transplant was less than 1 year vs between 1 and 2 years vs more than 2 years. Patients were requested to solution questionnaires for 7 days following dose 1 and dose 2. The responses showed that the 2 2 vaccine injections were very safe. Only grade 1 or 2 2 adverse reactions occurred in 51 of 106 patients (48%) after dose 1 and 34 of 87 patients (39%) after dose 2. These rates were comparable to those for a healthy vaccinated populace of 25 caregivers from your hematology department of Nantes University or college Hospital, who all achieved the highest IgG titer after the second dose. Finally, at a.