Progress toward a pathogen-free blood supply.

Although the nation's blood supply is safer than ever, a small risk of transfusion-transmitted infection remains. Present strategies to further reduce the risk, such as the donor medical evaluation or laboratory testing, will not likely eliminate this risk. A different approach involves treating donated blood to eliminate its infectivity. A pathogen-inactivated plasma product was available for several years but was recently withdrawn. Several other methods are under development, but all of these prevent nucleic acids from replicating, thus inactivating any contaminating viruses or bacteria. Toxicity, mutagenicity, and safety margins seem to be adequate, and damage to blood proteins or cellular elements is minimal. Clinical trials of pathogen-inactivated platelets have been completed in Europe and in the United States, and phase III clinical trials of pathogen-inactivated red blood cells are underway in the United States. If these encouraging results are sustained, the risk of transfusion-transmitted disease may be nearly eliminated.