Seroconversion to mRNA SARS-CoV-2 vaccines in patients with autoimmune cytopenias and bone marrow failures.

Data concerning the efficacy of SARS-CoV-2 vaccines in patients with non-oncological hematologic conditions are lacking. These include autoimmune cytopenias (autoimmune hemolytic anemia AIHA, immune thrombocytopenia ITP, and autoimmune neutropenia), and bone marrow failure syndromes (aplastic anemia, low risk myelodysplastic syndromes, and paroxysmal nocturnal hemoglobinuria). These conditions may relapse/reactivate after COVID-19 infection and vaccine. Moreover, they are mainly handled with immunosuppressive drugs that may hamper the response to vaccine. In this study, we prospectively evaluated the rate of seroconversion after mRNA SARS-CoV-2 vaccines in patients with autoimmune cytopenias or bone marrow failure syndrome after 2 ± 1 months from the last vaccine dose. Overall, 149 patients were tested and 135 (91%) seroconverted. The highest proportion of non-responders was observed in Evans syndrome (association of ITP and AIHA) and warm AIHA patients (p = 0.001), in those with lower levels of baseline serum IgG (p = 0.008), and in patients on active therapy with steroids (p = 0.03) who also had lower anti-Spike titers. The latter were inversely related with age, and a positively with lymphocyte counts. Additionally, patients who had received rituximab within 12 months from vaccination showed higher rates of non-response (p = 0.03) as compared to those treated before. Contrarily, cyclosporine alone, complement inhibitors, and bone marrow stimulating agents had no detrimental effect on seroconversion. These data suggest maintaining high vigilance and adherence to preventive/protective measures in this population since a proportion of cases may not respond or exhibit low anti-Spike titers.