Residual transfusion risk for hepatitis B and C in southern Brazil, 1991-99

A retrospective study of 139188 blood donor records for the period 1991-99 was conducted in the largest blood bank in the federal state of Santa Catarina, in southern Brazil. The incidence/window method, based on 11286 repeat donors with 8917 person-years of follow-up, was used to estimate the residual risk for transfusing hepatitis B and C due to infectious window periods for early, mid and late years of the decade. The residual risk for transfusing HBsAg contaminated blood decreased almost three times over the 1990 decade but still remains very high at 1 : 2077 (95% confidence limits 1 : 1075-1 : 4624), with a corresponding incidence of 3.00 (1.35-5.77) per 1000 person-years. Similarly, although residual risk for hepatitis C was reduced more than 30 times in late 1990s, compared with the earlier period, the risk of 1 : 13721 (1 : 7102-1 : 30820) and corresponding incidence of 0.51 (0.23-0.99) per 1000 person-years are still very high compared to developed countries. In addition to vaccination against hepatitis B and health promotion efforts aimed at reduction of hepatitis transmission, special measures such as PCR screening of pooled blood donations might be needed to rapidly achieve a further residual risk reduction in high prevalence areas.