Direct assessment of cytomegalovirus transfusion-transmitted risks after universal leukoreduction

Background: Cytomegalovirus (CMV) transfusion-transmitted disease (TTD) remains a clinical concern. Universal leukoreduction has become one of the main strategies for the prevention of CMV-TTD. Through prospective clinical follow-up and testing of transfusion recipients (TRs), the risk for CMV-TTD was studied. Study design and methods: Transfused units were all leukoreduced and not prospectively screened for CMV. For TRs with negative baseline CMV testing results (CMV total antibody and DNA), all follow-up TR samples were tested for CMV total antibody and DNA, and retained linked donor serum samples were tested for CMV total antibody. In cases when CMV-TTD was suspected, donor sera were also tested for CMV DNA and selected TR samples were tested for CMV immunoglobulin M antibody. Evaluable transfusion was defined as a transfusion with TR sample(s) collected 14 to 180 days posttransfusion. Results: Forty-six TRs were negative for CMV at baseline. There were 1316 evaluable cellular blood transfusions to these TRs. Of 1316 evaluable cellular products, 460 (35%) were positive for CMV total antibody tested using linked donor samples. Three cases of probable CMV-TTD were found; however, there was no definitive proof from donor follow-up that they were transfusion associated. Conclusion: Among all 46 baseline seronegative recipients and 1316 evaluable transfusions, the calculated overall CMV-TTD risk was up to 6.5% (95% confidence interval CI, 1.0%-18.0%) in terms of TRs and up to 0.23% (95% CI, 0.06%-0.62%) in terms of non-CMV-screened leukoreduced cellular products. In summary, after universal leukoreduction, CMV-TTD, while uncommon, may still occur.