How much would the safety of blood transfusion be improved by including p24 antigen in the battery of tests?

Abstract

Because p24 antigen may be detectable during seroconversion, before antibodies, some of the infected blood undetected by antibody screening could be identified through antigen screening. The potential benefit of antigen screening was evaluated in a simulation model incorporating present knowledge of the time sequence from antigen exposure to antibody development during seroconversion and the incidence of seroconversion among repeat donors. The model was designed so that the results were consistent with the observed rate of antibody-positive blood donations and the CIs of surveys that did not find any antibody-negative/antigen-positive donated blood. In the United States in 1990, the number of expected, undetected, contaminated blood components was estimated at 68; of these 8 to 17 could have been identified by antigen screening, depending on the hypothesis explored. (In 1992, 20 undetected, contaminated blood components were expected according to this model, of which 2 to 5 could have been 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. The projected benefit must be weighted against possible negative consequences, including 1) an increase in recently infected persons seeking p24 antigen screening at blood banks (assuming this test is not incorporated into screening in non-blood bank settings) and 2) the need for additional quality assurance procedures to avoid operational flaws associated with the increase in the donor screening test battery. In any case, the best way of increasing the safety of blood is improvement in the selection of donors, which can diminish the residual risk of transmission of any viruses.