All successful donations were subjected to tests on two different HBsAg assays by an enzyme-linked immuno sorbent assay (ELISA). If both testing on the two different HBsAg assays were reactive, the screening test was defined as reactive. If the results from either one of two tests was reactive, the sample was retested in duplicate on the same assay and/or another appropriate kit. The screening test was defined as reactive if either one or two positive reactive results were obtained during retesting of the HBsAg ELISA tests. If both tests showed non-reactive results, the screening test was defined as non-reactive, and the corresponding donation was qualified for transfusion.