Residual risk of transfusion-transmitted HCV and HIV infection by antibody-screened blood in Italy

BACKGROUND: This study was designed to assess the risk of transmitting HCV and HIV by transfusion of antibody-screened blood and to estimate the additional reduction in risk that may be achieved through the implementation of direct viral detection assays in Italy. STUDY DESIGN AND METHODS: Clinical and laboratory data of 2,411,800 blood donations collected from repeat volunteer donors from 1996 through 2000 were analyzed. The risk of transmitting HCV or HIV from screened blood donated during the window period was estimated using a mathematical model. RESULTS: The residual risk of donating antibody-negative infectious blood was estimated at 1 in 127,000 donations for HCV and 1 in 435,000 for HIV. The use of NAT should further reduce such risk by 83 percent for HCV and 50 percent for HIV. CONCLUSION: The residual risk of HCV or HIV transmission through screened blood is currently very small in Italy. The implementation of direct viral detection assays can further improve the safety of blood supply.