INCIDENCE OF SEROCONVERSION TO POSITIVITY FOR HEPATITIS-C ANTIBODY INREPEAT BLOOD-DONORS IN ENGLAND, 1993-5

Objective: To estimate the rate of seroconversion to positivity for he patitis C antibody in repeat blood donors in England and to describe t he probable routes of infection in these donors. Design: Retrospective survey of blood donors becoming positive for hepatitis C antibody and of the results of donation testing. Setting: The 14 blood centres in England. Subjects: All repeat donors giving blood between January 1993 and December 1995. Main outcome measures: Number of donors developing hepatitis C between donations during the three years of testing for h epatitis C antibody at English blood centres and the rate of seroconve rsion among repeat blood donors. Probable routes of infection. Results : 14 donors during 1993-5 fulfilled the case definition for seroconver sion to positivity for hepatitis C antibody. The estimated seroconvers ion rate for infection with hepatitis C in repeat donors was 0.26 per 100 000 person years (95% confidence interval 0.15 to 0.43). Counselli ng after diagnosis found that four of these donors had risk factors sp ecified in the criteria excluding people from giving blood but these f actors had not come to light before donation. Another of the donors wh o seroconverted had a risk factor that has since been included in the exclusion criteria. Heterosexual intercourse was considered to be the most likely route of infection for five of the 14 donors. Conclusions: The rate of seroconversion for positivity to hepatitis C antibody in repeat blood donors in England was extremely low. During 1993-5 fewer than 1 in 450 000 donations were estimated to have come from repeat do nors who had become positive for hepatitis C antibody since the previo us donation.