Transmission of cytomegalovirus (CMV) infection by leukoreduced blood products not tested for CMV antibodies: a single-center prospective study in high-risk patients undergoing allogeneic hematopoietic stem cell transplantation (CME)

BACKGROUND: Measures to prevent transfusion‐transmitted cytomegalovirus (TT‐CMV) infection after hematopoietic stem cell transplantation (HSCT) include transfusion of CMV antibody–negative blood units and/or transfusion of leukoreduced cellular blood products. We assessed the incidence of TT‐CMV in CMV‐seronegative patients receiving CMV‐seronegative HSC transplants, who were transfused with leukoreduced cellular blood products not tested for anti‐CMV. STUDY DESIGN AND METHODS: In a prospective observational study between 1999 and 2009, all HSCT patients received leukoreduced cellular blood products not tested for anti‐CMV. Patients were screened for CMV serostatus and CMV‐negative recipients of CMV‐negative transplants were systematically monitored for TT‐CMV clinically and by CMV nucleic acid testing. Anti‐CMV antibodies (immunoglobulin Ig]G and IgM) were assessed after three time intervals (Interval 1, study inclusion to Day +30 after HSCT; Interval 2, Day +30‐Day +100; Interval 3, after Day +100). RESULTS: Among 142 patients treated with allogeneic HSCT, 23 CMV‐negative donor‐patient pairs were identified. These 23 patients received 1847 blood products from 3180 donors. All patients remained negative for CMV DNA and none developed CMV‐associated clinical complications. This results in a risk for TT‐CMV per donor exposure of 0% (95% confidence interval, 0.0%‐0.12%). However, 17 of 23 patients seroconverted for anti‐CMV IgG, but none for anti‐CMV IgM. CMV IgG seroconverters received significantly more transfusions per week than nonconverters. CONCLUSION: The risk of TT‐CMV is low in high‐risk CMV^neg/neg HSCT patients transfused with leukoreduced blood products not tested for anti‐CMV. The cause of anti‐CMV IgG seroconversion is most likely passive antibody transmission by blood products.