Nucleic Acid Testing (NAT) is the newest technology available to increase the safety of the blood supply. It utilizes the ability of laboratories to isolate and detect genetic material from deadly viruses such as Human Immunodeficiency Virus (HIV), Hepatitis C Virus (HCV), and West Nile Virus (WNV).
The Blood Center has been using NAT since 1999 for HIV and HCV, and since 2003 for WNV.
Previous testing methods involved the detection of antibodies that the body produces in response to an infection. The main problem with these methods is that the body took a certain amount of time to produce detectable amounts of these antibodies. This period of time, from the time someone is infected, to the time that they have produced enough antibodies for the laboratory to detect, is called the “seroconversion window” or the “window period”. In some cases, such as with the HCV, this “window period” could be on the average of 70 days!
In addition to the “window period”, antibody testing had a very high rate of false-positives. To err on the side of safety, screening tests for HIV, HCV, Hepatitis B Virus (HBV) and Human T-Lymphotrophic Virus (HTLV) were designed to detect as many positive donors as possible, including those with very low levels of antibodies. Unfortunately, perfectly healthy donors sometimes tested positive for these tests as test manufacturers sacrificed test specificity to gain test sensitivity.
The advantage of NAT is that it is sensitive and specific! For example, HCV can be detected on average 60 days sooner than previous antibody testing, and HIV can be detected on average five-days sooner. When WNV proved to be a potential risk to the blood supply, NAT was the obvious choice as the testing method to be used.
Unfortunately, there is no test available that can detect viruses immediately after someone has been infected, but NAT has dramatically closed that window. As newer technologies become available, you can be assured that The Blood Center will be at the forefront, increasing the safety of the blood it supplies to the hospitals it serves.
