HOW MUCH WOULD THE SAFETY OF BLOOD-TRANSFUSION BE IMPROVED BY INCLUDING P24 ANTIGEN IN THE BATTERY OF TESTS

Background: Because p24 antigen may be detectable during seroconversio n, before antibodies, some of the infected blood undetected by antibod y screening could be identified through antigen screening. Study Desig n and Methods: The potential benefit of antigen screening was evaluate d in a simulation model incorporating present knowledge of the time se quence from antigen exposure to antibody development during seroconver sion and the incidence of seroconversion among repeat donors. The mode l was designed so that the results were consistent with the observed r ate of antibody-positive blood donations and the Cls of surveys that d id not find any antibody-negative/antigen-positive donated blood. Resu lts: In the United States in 1990, the number of expected, undetected, contaminated blood components was estimated at 68; of these 8 to 17 c ould have been identified by antigen screening, depending on the hypot hesis explored. (In 1992, 20 undetected, contaminated blood components were expected according to this model, of which 2 to 5 could have bee n identified by antigen screening.) In France, the comparable figures were 1 to 4 of 13 in 1990 and 1 to 2 of 7 in 1992. Conclusion:The proj ected benefit must be weighted against possible negative consequences, Including 1) an increase in recently infected persons seeking p24 ant igen screening at blood banks (assuming this test is not incorporated into screening in non-blood bank settings) and 2) the need for additio nal quality assurance procedures to avoid operational flaws associated with the increase in the donor screening test battery. In any case, t he best way of increasing the safety of blood is improvement in the se lection of donors, which can diminish the residual risk of transmissio n of any viruses.