ABSTRACT
Rates of disease transmission could previously be measured by simply following transfusion recipients over time.1 Current viral disease transmission rates are now too low to measure, so that mathematical models2,3
are needed to estimate blood risks. The models are based on the fact that disease transmission is thought to occur primarily in the window period (the time after a blood donor is infectious but before any donor screening tests are positive). These models also disregard the fact that, as a result of underlying disease, patients who receive transfusions have 1-year and 10-year mortality rates of about 24% and 52%, respectively, and may not live long enough to develop transfusion-transmitted disease.4 The estimates are measured on relatively small numbers with wide confidence intervals, and thus there is some uncertainty in transfusion transmission rates.2 Nevertheless, estimated risks of transfusion-transmitted diseases for immunocompetent patients (Table 23.1)5 are lower than ever before and have been summarized recently.6,7 These risks have declined substantially with implementation of nucleic acid testing (NAT), which has shortened infectious window periods and dramatically reduced the current estimated risks of post-transfusion infection with hepatitis C virus (HCV) and human immunodeficiency virus (HIV).
