Improving blood safety using fourth generation HIV ELISA as the screening tool in blood banks – an Indian experience

Results The HIV seroprevalence was estimated to be 1.37/1000 donations with 3 generation and 3.62/1000 donations with 4 generation ELISA (p>0.05). Of the 17 samples which were 4 generation ELISA positive and WB positive, 11 were positive with 3 generation ELISA. Fourth generation ELISA tested 19 additional samples positive and 7 samples as possibly positive which were tested negative with 3 generation ELISA, giving an additional yield of 26 window period units per 10200 donations i.e. 2.5/1000 donations. Of these, 6 were WB positive giving a yield of 0.58 window period units per 1000 donations. Since 2-3 components are prepared from each blood unit, the yield can be increased to 12-18/10200 donations. With an annual donation of nearly 46000 blood units, this will be 54-81 positive samples per 10200 donations.