Hepatitis‐Associated Markers in the American Red Cross Volunteer Blood Donor Population

From January 1975 to December 1978, 19,140,169 units of blood were collected by the American Red Cross at 57 regional locations. Each unit was tested for hepatitis B surface antigen (HBsAg) by a single commercial radioimmunoassay test system. A total of 15,954 donations were reported reactive, representing a rate of HBsAg reactivity of 0.83/1,000 units tested. The rate during 1975 was 0.94/1,000 units tested, decreasing to 0.71/1,000 units tested in 1978 (p < 0.005). The prevalence of HBsAg among first-time donors was 2.08/1,000 during 1977 and 1978, 2.7 times higher than that calculated for repeat donors (0.77/1,000 donors). Substantial geographic variation in the prevalence and rate of detection of HBsAg was observed.