US NAT yield: where are we after 2 years?

The US blood supply has been tested for human immunodeficiency virus-1 (HIV-1) and hepatitis C virus (HCV) using nucleic acid amplification testing (NAT) of pools of small number of samples since early 1999. Since the implementation of NAT under an investigational new drug (IND) application, the results for the yield and false positivity have been remarkably consistent for greater than 2 years of testing even among multiple programmes using two different test methodologies and manufacturers: Gen-Probe/Chiron transcription-mediated amplification (TMA) and Roche polymerase chain reaction. All programmes in the US and Canada use NAT as a criterion for cellular as well as frozen product release. The focus of this paper is to provide an update of the programmes in the US and Canada, provide data in support of p24 antigen replacement by HIV-1 NAT and discuss the projections of residual risk of HIV, HCV and hepatitis B virus (HBV) following NAT and the associated cost/benefit.