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 models (2,3) 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 due to 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). Estimated risks of transfusion-transmitted diseases (5) are lower than ever before (6,7). These risks have declined substantially by the implementation of nucleic acid testing (NAT) that has shortened infectious window periods and has substantially reduced the estimated risks of posttransfusion hepatitis C and Human immunodeficiency virus (HIV) (Table 1).
