The reduction of HIV transfusion risk in southern Brazil in the 1990s

A retrospective study of blood donor records was undertaken to obtain risk estimates for transfusing HIV-contaminated blood due to an infectious window period in a large blood bank in the south of Brazil in the 1990s. An incidence/window period model was used to estimate HIV incidence and risk of seroconversion among 11 286 repeat donors with 8917 person-years of follow-up. Separate estimates were calculated for the periods of 1991-94, 1995-96 and 1997-99. Although the residual risk of HIV-positive transfusion decreased from 1 : 5000 in 1991-94 and 1 : 3794 in 1995-96 to 1 : 48 777 in 1997-99, this is still almost 10 times higher than in developed countries. The risk reduction is likely to have resulted from improved donor selection. Despite a 10-fold reduction in the risk of transfusing HIV-contaminated blood because of the screening test's failure to detect the virus during the infectious window period in the 1990s, additional measures are urgently needed to reduce the risk further. To this end, PCR screening of pooled blood donations might be considered in areas of high HIV prevalence when justified by cost-effectiveness calculations.