HIV Tests - Peace of Mind

[Shark4411]

Dr HH,
What would be a safe window period to take these tests to have peace of mind after a sex exposure:
1) Combo (antibody+antigen)
2) PCR RNA Viral Load

I heard the following:
1) Combo - 1 month
2) PCR RNA Viral Load - 2 weeks

Do you think it needs to be longer than that?

Thx

[H. Hunter Handsfield, M.D.]

I disagree with parts of Nacido's comments and therefore deleted them.

I didn't say you "should" be concerned about false negative.  You said you were worried about having a false positive result.  All your results were negative -- so if any result was false, it was false negative, not false positive.

Re-read my replies above.  You don't have HIV, period.  Thats' all for this thread.

[Shark4411]

Dr HH.
Re-reading your answer a doubt came up. Why should I be worried of false negative. I did the test at the best Lab in the country.

[Shark4411]

Thanks a lot

[H. Hunter Handsfield, M.D.]

Your concern is for a false negative result, not false positive.  In any case, it is impossible to have HIV with all 3 negative results you describe (PCR at 2 weeks, p24 antigen and antibody at 4 weeks).  If you carefully read the threads whose links I provided, you will see that p24 antigen cannot go away before antibody develops.  It's the antibody itself that clears p24 out of the blood.

In other words, your results are 100% reliable.  You're home free.  You can stop worrying about it and stop testing.

[Shark4411]

Dear Dr HH

Thanks for the answer and for the additional links.
Given what you said, and considering that I had a negative on both test, do you think any further test is needed? The precise date that I took the combo was the 33rd day after exposure. I had a similar worry that on the 33rd the p24 could have disappeared and the antibodies wouldn't be detectable yet. Can this case happen?
When taking tests, what worries me the most is the risk of a false positive. How about that?

Regds

[H. Hunter Handsfield, M.D.]

Welcome to the forum.

You "heard" correctly.  The combo test (HIV antibody and p24 antigen) is virtually 100% reliable by 4 weeks after exposure.  The viral load test has been less carefully studied in this context, but 2 weeks is about right.  Antibody-only tests are almost 100% certain by 6-8 weeks.  However, in some cases with especially high risk exposure (e.g., unprotected vaginal or anal sex with a known infected partner), later testing may be warranted.

Below are two recent threads that discuss these issues in more detail.  For other discussions, you can also use the search function and enter such terms as "window period" or "seroconversion".  Or just look at any 10-15 threads at random; probably almost half of all questions on this forum have an element of HIV test timing.

http://www.medhelp.org/posts/HIV-Prevention/Need-your-help/show/1345664
http://www.medhelp.org/posts/HIV-Prevention/-A-Question-on-Testing/show/1347755

Regards--  HHH, MD