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Accuracy of PCR negative test??? Please help!

Aug 21, 2007

Hello Mr.Frascino, first of all thank you very much for all your fantastic job that you do every day. I have been reading your answers, and they are very useful but I didn't find any answer for my question:

I know that you don't recommend the PCR test and, for a low risk exposure, it's recommended the ELISA test after 3 months. Anyway, it's 3 weeks since the low risk exposure and I wonder if a PCR negative test would give me an accuracy of 99,9% that I am not HIV+.

I know that this test can give false positive results but, what is the accuracy in the case of a negative result after 3 weeks? Somebody told me that, although PCR it is not recommended, in cases with negatives it is very reliable.

Thank you very much, a donation will be made. I am sorry for my bad English, you are read worldwide: even from Europe. THANKS A LOT again

Response from Dr. Frascino


You are correct: PCR testing is not recommended for routine HIV screening, due to the rate of false-positives, other technical considerations and cost. Consequently, since it is not recommended for routine HIV screening, I have no way of advising you of the test's accuracy at three weeks. What I can say is that false-positives are much more of a problem than false-negatives when using PCR technology. Also, as you noted in your question, if you want to get a definitive answer regarding your HIV serostatus, "it is recommended you get an ELISA test after three months." That is exactly what I recommend you do.

Thanks for your donation to The Robert James Frascino AIDS Foundation ( In return I'll send my good-luck karma that your three-month definitive HIV-antibody test is negative. I strongly believe it indeed will be negative!

Good luck.

Dr. Bob

OCD may get the best of me
Getting PEP in Buenos Aires

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