Welcome to the HIV forum.
Dr. Bob Frascino is a knowledgeable guy and runs a great forum. Although we have different styles, our perspectives on HIV transmission risk, test interpretation, etc are similar. Also, you had accurate responses to this question on the HIV community forum.
However, I don't understand exactly what you're asking. If you are simply saying that some user says s/he is aware of a case where it apparently took longer than 3 months for an HIV test to become positive, I would just disregard it. If that happens, it is too rare to worry about -- and most likely s/he just isn't correctly stating the facts.
With HIV antibody tests in current use, almost all newly infected people have positive results within 6 weeks; testing as late as 3 months usually isn't necessary -- but many health agencies continue to say 3 months, and some even say 6 months, for exactly the reason you state: CYA advice from the legal department (One slight difference between Dr. Frascino and me or Dr. Hook may be that last I scanned his forum, he still emphasized 3 months, whereas we are usually happy with 6 weeks as sufficiently long for reliable results.)
Of the factors you mention that could alter this, PEP is the one that makes most sense. It is logical to suppose that if someone is exposed to HIV and gets PEP but it doesn't work, HIV seroconversion might be delayed. But there have been no research reports on this. My guess is that if seroconversion is delayed, it's shifted by a couple of weeks, not 6 months.
There is no measurable difference between 87 days and 3 full months (90-93 days). You can consider your negative test as 100% reliable.
I hope this helps. Best wishes-- HHH, MD
"However, I don't understand exactly what you're asking. If you are simply saying that some user says s/he is aware of a case where it apparently took longer than 3 months for an HIV test to become positive, I would just disregard it." ----- what i was saying (to be more clear, i apologize) is that a person had a risk and had an exposure with an HIV positive person, in response dr. Bob tells that person to test at 3 months and then again at 6 months (in a different scenario where the person at risk didn't have KNOWN positive he just says 3 months). I wasn't implying that someone said that they tested positive after 3 months.
As for when to test, i actually thought it was 12 weeks not 13 weeks. I guess it depends on what interpretation of 3 months i presume (or maybe US thing). Im still uneasy about the reliability of the 3 months antibody test with comments about 6 months. I see from you two good doctors that "it never takes longer than 3 months" or "with modern test everyone is positive by 12 weeks" to name a few. If that is the case why a doctor (like dr. bob) even recommend 6 months, i know he says he follows guidelines of the CDC (from what he says) but why do that if the tests pick up everyone at that point that isn't on PEP or (theoretical) on Chemo etc. Why put people through more misery just because old tests might miss some? Given from my own research that from what i have read, the UK haven't had false negative beyond 12 weeks in almost 12 years (modern tests) and Dr bob never has seen false neg at same time and i believe same goes from your experience as well if i remember correctly. That seems like MANY years from many doctors with no failures (baring extenuating circumstances). Either the 3 month antibody test picks up everyone except the few exceptions because of PEP or some really due slip through, if so everyone should test at a later date do be sure.
Sorry for the rant but it is a little frustrating as im sure just as equally frustrating answering this similar question daily, im a pretty sensible person with a level head yet this whole testing time makes my brain hurt.
Although my interactions is with dr hhh ide love your input and/or dr hook, I appreciate it.
OK, now I get it. Dr. Bob is simply saying that when the risk of HIV infection is particularly high, it is sometimes wise to have an extra test at the lastest possible time. We do the same thing here. Even though we almost always say 6-8 weeks is plenty of time, when someone is at particularly high risk, we advise testing at 3 months.
Why should testing time be linked with risk? Because our advice, and Dr. Bob's, takes into account not only test performance, but also the chance of HIV even before the test is done. Here is how it works.
Scenario A: Let's say the chance a particular partner has HIV is 1 in 1,000 and there was a 1 in 1,1000 chance of transmission. (These are pretty good ballpark figures for a single episode of unprotected vaginal sex in the US or other industrialized country.) Even without testing, the chance such a person has HIV is 0.001 x 0.001 = 0.000001, or 1 in a million. If that person then has a 4 week test, which will pick up around 90% of infections, his or her chance of having HIV -- after the test result -- is 1 in 10 million. Most people will (or should be) happy with those odds, so no further testing is needed, even though the test is only 90% sensitive at 4 weeks.
Scenario B: Now assume a known HIV infected partner has unprotected anal sex. The receptive partner has a 1% chance of catching HIV, or 1 in 100. If a test at 4 weeks is negative, his chance of being infected drops to 1 in 1,000. A lot better than 1 in 100, but obviously not good enough. Same test, done at the same time after exposure, but a very different level of reassurance. This person clearly needs another test or two. Even at 6-8 weeks, when the test picks up nearly all (let's say 99%) of infections, the chance he has HIV is still 1 in 10,000. Better still, but good enough? Maybe not. Thefore, Dr. Hook or I would recommend a 3 month test. Dr. Bob apparently is even more conservative and would recommend a 6 month test.
Finally, you're always going to find differences between equally qualified experts and health agencies about 12 versus 13 weeks, 3 versus 6 months, and the like. The reason is that the exact performance of the HIV tests really isn't known with that much precision. And there will never be research that provides much more detail; the same uncertainties will be there i10 or 20 years from now. It just isn't worth the time and expense; the required research study would cost millions of dollars. But for sure there is no practical difference between 12 and 13 weeks and probably not between 3 months and 6 months.
This has been explained several times on the forum, but not for a while. Thanks for the opportunity to explain it again.
Dr. Hook won't comment. We have been close colleagues for 3 decades, and although our styles differ, our opinions and advice almost never do. And we are definitely in agreement on this issue.
Going back to your situation: Clearly you don't have HIV. Don't overthink all this business. Time to move on. Of course you are free to be restested whenever and however often you wish if you need the additional psychological reassurance of additional negative results. It's your money.
That will be all for this thread. I'm tired.
Thanks sir..much appreciated.
I appologize for commenting again for it will be my final post on this thread and subject. I realize that the 3rd generation hiv tests may theoretically miss infections beyond 3 months and probably due to some other illness or PEP but in the real world where tests are being used does it actually happen, I hear that bigfoot is possible but with few cases seen and ever documented its hard to set in stone something is. real or happens when there is no real evidence to support such a theory. Is there any evidence to support tests beyond 3 months with modern testing? I see all the time where you and dr hook mention where this never happens or the idea of delayed antibody production beyond 3 months is an urban myth, is this the bigfoot effect? Lastly for percentile figures I have seen showing a 98 to 99% of people picked up at about 8 weeks, how is it possible that in 8 weeks modern tests picke just about 100% of people yet you need to test again at 6 months to be 100% with known positive, as dr bob states, is it me or does that seem very silly that while 8 weeks pick up 98% that the body need another 3 months and 5 weeks I'm order to pick up 2%. Is it just me or does that not sound right. In closing I hope you can answer these final questions that had me very curious for awhile and do appologize for the lenght of the posts and maybe a little repetative statments yet I needed to get across my point/idea to you. Thankyou for your thoughts and time, I hope you enjoy the rest of this Sunday dr(s).