Prevalence, incidence, and residual risk of human immunodeficiency virus and hepatitis C virus infections among United States blood donors since the introduction of nucleic acid testing

BACKGROUND: Nucleic acid testing (NAT) for human immunodeficiency virus (HIV) and hepatitis C virus (HCV) was introduced for blood donation screening in the United States in 1999. This study analyzes temporal trends of these two infections since NAT introduction. STUDY DESIGN AND METHODS: Donation data from 1999 to 2008 were analyzed; each donation was tested for antibodies and viral RNA for HIV and HCV. Incidence for first-time (FT) donors was derived by multiplying that among repeat (RP) donors by the ratio of NAT yield rates between FT and RP donors. Incidence for all donors was the weighted mean based on percentage of FT and RP donors. Residual risk (RR) was determined using the window-period model. RESULTS: During the 10-year period approximately 66 million donations were screened with 32 HIV (1:2 million) and 244 HCV (1:270,000) NAT yield donations identified. HCV prevalence among FT donors decreased by 53% for 2008 compared to 1999. HIV and HCV incidence among RP donors increased in 2007 through 2008 compared to 2005 through 2006. During 2007 through 2008, HIV incidence was 3.1 per 10(5) person-years (py), with an RR estimate of 0.68 per 10(6) (1:1,467,000) donations; HCV incidence was 5.1 per 10(5) py, with an RR estimate of 0.87 per 10(6) (1:1,149,000). The increase in HIV incidence was primarily among 16- to 19-year-old, male African American donors and that in HCV was primarily among Caucasian donors of 50 or more years. Donors from the Southern United States had higher incidence rates. CONCLUSION: HCV prevalence decreased significantly since NAT introduction. The increase in HIV and HCV incidence in 2007 through 2008 warrants continued monitoring and investigation.