HIV - Prevention Expert Forum
Naat HIV Test
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This forum is limited to prevention of HIV and to safe sex in general. All questions will be answered by H. Hunter Handsfield, M.D. or Edward W Hook, MD.

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Naat HIV Test

The clinic I went to be tested does a Naat Test for HIV. I know from my research that it is a good test for early detection because it has a shortened window period. Is there a time after which the test is not reliable? For instance, is the NAAT test not accurate or conclusive if done more than six months after exposure because of a decreased level of HIV in the blood?
239123_tn?1267651214
Welcome to the forum and thanks for your question.  This is a good opportunity for a brief blog-like response that can be saved to respond to future questions about HIV nucleic acid amplification testing (NAAT).

NAATs detect HIV DNA, i.e. a direct test for the virus itself.  NAAT was originally designed and used primarily to judge the response to treatment of HIV/AIDS and the extent to which the patient's immune system is controlling the infection.  Higher viral load as measured by NAAT means less good control, lower levels mean better control.

More recently, NAATs are being increasingly used to detect early HIV infection, because HIV DNA typically becomes detectable around 10-14 days after infection, sometimes as soon as 7 days.  However, standard practice is to always do an antibody test as well.  If NAAT testing is done alone, it should pick up just about all HIV infections, but there are exceptions -- especially in those few patients whose immune system controls the infection better than most.

So exactly as you suggest yourself, a NAAT might miss an HIV infection at 6 months or more after infection.  It's unlikely, but possible.  Therefore, I would recommend you also have an HIV antibody test.

Going back to early testing, a NAAT plus an antibody test is 100% reliable in ruling out HIV at 4 weeks or more after exposure, similar to the "combo" or "duo" test, which measures both HIV antibody and p24 antigen (which, like NAAT, is a test for the virus itself).  NAAT may be even better than p24 for this purpose.

Having said all that, NAAT is a lot more expensive and generally is not recommended to check for early infection except in especially high risk situations.  I'm a little surprised to hear it may be the primary test being performed at the clinic you attended; not many will take that position.  (But maybe you indeed had a particularly high risk exposure.)

I hope this has helped. Let me know if anything isn't clear.

Best wishes and stay safe--  HHH, MD
6 Comments
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Avatar_m_tn
I will have an rapid antibody teste done. It will be about a year after an exposure. Do I need to repeat the NAAT test?
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Avatar_m_tn
Do I need to rpeat the NAT test when I do the antibody test?
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Avatar_m_tn
I don't want to be a pest but I would like a clarification. I will do an rapid hiv antibody test but I do not want to repeat the NAT test?  The rapid antibody is after ten months.so will that alone be conclusive?
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Avatar_m_tn
I called the clinic and it did do an antibody test at the same time. I'm going for an antibody test at close to a year.  Is it okay if I only do that and not the nat test again. The antibody will be the clearview rapid test
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239123_tn?1267651214
Another antibody test is all you need.  If you have had at least one negative antibody test at 8 weeks or more after your last possible exposure, then for sure you do not have HIV and do not need any further testing.  If you get retested again at all, I would recommend another antibody test, not NAAT or anything else.

You have quite a track record of anxiety driven questions which in the past you have related to OCD.  Your current question has similar earmarks.  Please note that MedHelp allows a maximum of 2 questions every 6 months on each professionally moderated forum, in order to limit anxiety-driven questions and prevent domination of forums by a few users.  By my quick count, this is your 5th or 6th question on this forum in a little over a year.  It's going to have to be your last for at least a year.  Before next June, any new question from you will be deleted without reply, and without refund of the posting fee.

That will end this thread as well.  Keep working on that OCD!
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