[Question #4280] 7 vs. 8 weeks, no difference right?

30 months ago
Dear doctor. Thanks for the valuable service you provide. I imagine alot of patience to calm mild (and sometimes not so mild) anxieties over so many years. 

My context (and question below) are simple: I had protected intercourse (and unprotected oral, recieved bj) with a csw on Apr. 21. I know zero risk. On Jun. 8, 49 days after this encounter, I had a rapid blood test (blood drawn from vein, 15 min results) done which was negative. Thus I know, no need for testing in the first place, but can be 100% assured as a result of test, which was more as part of a overall checkup.

My only question is that you and many other experts now site 6-8 weeks as conclusive for a rapid test like I had, but why the range? i.e. is there any chance that someone like myself (negative at 49 days/7 weeks) could change in result at like 56 days/8 weeks? 

Again disappearing anxiety but also just curious. 
Edward W. Hook M.D.
Edward W. Hook M.D.
30 months ago
Welcome to the Forum. I will be glad to comment although I fear that the information I provide may not please you.  Among tests for HIV the "rapid", tests are the ones we favor least. They tend to be antibody only tests and are slightly less sensitive than other lab-based tests.  As a result our sense is the rapid blood tests should probably not be considered conclusive until 12 weeks after an exposure.  Your seven week test would have likely detected 85-90% of recent infections.  Our advice for conclusive tests is to seek testing with a combination HIV antigen/antibody test any time 6 weeks after an exposure. 

I hope that this information is helpful to you. EWH
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30 months ago
That makes sense regarding the testing, but as I mentioned regarding my exposure on Apr. 21, it was condom protected intercourse with brief unprotected bj. 

I still need testing?
Edward W. Hook M.D.
Edward W. Hook M.D.
30 months ago
Considering all that you indicate I see no medical or scientific reason for testing.  I would not bother to test if I were you.
EWH
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30 months ago
Dr, I am clear on my lack of risk and that I don't need testing. 

However, I want to clarify that in my original post, I was inquiring about a rapid blood test (NOT oral fluid) which I understand are all 3rd gen. 

In post 3354) you mention "you can have confidence that your 3rd generation HIV test at 8.5 weeks (referring to vikia rapid test) has provided accurate results.  There is no need for additional testing."

In post 298) dr. hhh mentions that while the standalone antibody tests, including rapid require, 3 mo to be conclusive from the manufacturers, "clinical experience and most experts' advice is that they are conclusive by 6 weeks. The negative results at 38 and 56 days prove you don't have HIV."

Thus  I'm a bit lost on the discrepancy? Thanks in advance for this final response. 

Edward W. Hook M.D.
Edward W. Hook M.D.
30 months ago
Thanks for your clarification.  You are correct, the problem with the rapid tests is with the oral fluid tests and that was what I wrote about.  My confusion led to a more conservative statement than was appropriate.  You can have confidence in your 49 day test result.  Considering your result and the nature of your exposure, you can be confident that results will not change.  There is no need for further testing.  EWH
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30 months ago
Thanks doctor. You can close out this thread!