To the Editor: Imagawa et al. (June 1 issue)1 reported that some persons infected with human immunodeficiency virus type 1 (HIV-1) may remain seronegative for prolonged periods. Haseltine,2 in an accompanying editorial, reviewed regulatory viral genes that may explain silent HIV-1 infections. The authors of both articles commented on the potential relevance of these findings to the safety of the blood supply. Unfortunately, they did not provide data addressing the differences between the criteria used in their epidemiologic study and well-established procedures currently applied in screening blood donors. For instance, the authors considered as negative all samples that were reactive….