Old and new tests: where will it end?

Testing has improved the safety of the blood supply. We have excellent serologic tests in place now and are implementing nucleic acid based tests to identify asymptomatic carriers of viruses during the infectious part of the pre-seroconversion (window) period. However, the blood supply was already quite safe after a variety of other mechanisms had been put into place besides testing to screen out individuals at risk of carrying the most important transfusion transmissible agents. An important safety factor is the use of volunteer, unpaid (unremunerated) blood donors. The best alternative to implementing yet more tests to reduce, but not eliminate, the minute residual risks of transfusion transmission of such agents as HIV, HBV and HCV is the application of microbial inactivation technology to blood and blood components. Such microbially inactivated, cellular blood components should not have the risk of transmitting infectious agents, but may have other, different risks, since nothing has yet been shown to be one hundred percent safe (i.e., risk free). The use of a test to detect carriers of spongiform encephalopathies to prevent their theoretical transmission by transfusion may cause harm to donors and might increase risk for recipients by decreasing the available blood supply.