[Question #8221] Testing After PEP
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47 months ago
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Let me start off by saying thank you to Dr. Hook and Dr. HHH for having this forum. It has been so helpful to me after I had some poor information given to me. I had an exposure that I rather not go into to much detail about if possible. After the exposure I was immediately tested via AG/AB test and it came back negative and was referred to an infectious disease doctor. He ended up giving me pep at 45 hours after exposure and also had me take a RNA test 20 copies/ml 12 days post exposure. I had done a little research on my own and questioned the reliability of this test while being on pep. He said he had never heard of it affecting the test since it would look for the virus in the blood and said if the test is negative finish pep and then continue my testing with my doctor. The test was negative and obviously I found out later that test was not accurate. So 16 days after finishing pep I have now tested negative on another RNA test 20 copies/ml as well as a AG/AB test.
1. I know these tests are not conclusive especially the AG/AB test but how confident should I feel about the RNA test 16 days after pep? I'm very aware that due to pep the testing times are altered.
2. If piece of mind is all I care about and I pay for my own tests. How accurate do you think and additional RNA test would 30 days after pep? And would there be any benefit in doing and AG/AB test at the same time?
3. In another thread Dr. HHH says he exchanged emails with an expert who researches PEP and HIV and she considers a AG/AB test at 6 weeks after pep to be conclusive. It this still considered true?
4. From the animal studies it appears pep isn't very effective past the 36 hour mark. Yet I continually read that the time frame is up to 72 hours. Is it kind of just a hail mary after the 36 hours?
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H. Hunter Handsfield, MD
47 months ago
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Welcome to the forum. Thanks for your kind words about our services.
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As you seem to understand, there are few data on testing standards and outcomes in association with PEP. For a variety of reasons, it's a difficult issue to study, so most available information is based on personal experiences of physicians and clinics plus general principles about the biology of HIV infection and how the antiretroviral (ARV) drugs work. To clarify your opening comments, I believe you mean that the RNA tests showed under the detectable level of 20 copies/ml, i.e. negative, no viral RNA detected. You also seem to understand that I might be able to advise you better if you would like to say more about the nature of your exposure. Finally, I don't think it is correct to say that either of your RNA tests was "not accurate". The test result undoubtedly is valid, i.e. no viral RNA detected. However, when done while taking ARVs it may not rule out the possibility you were infected. Now to your specific questions:
1. The large majority of newly infected people probably would have positive RNA tests 2 weeks after completion of PEP, so that result is very reassuring, although perhaps not conclusive.
2,3. A negative AgAb test at 30 days probably would be sufficient and conclusive, with or without another RNA test, but some experts would retest at 6 weeks. And some would go as long as 3 months. Personally, I doubt 3 months is necessary, but it is difficult to be 100% confident without better data. (One of the downsides of PEP, which often is not considered when PEP is prescribed, is the resulting delay in conclusive testing and hence prolonged anxiety about the outcome. It's perhaps the main reason PEP shouldn't be used when the exposure was low risk.)
4. As best I know, the 72 hr limit is simply one of practicality: it can often take that long for exposed persons to identify resources, arrange for the first clinic visit, etc. From the animal models, it is apparent that the sooner treatment is started, the better. However, I am unaware of any data in exposed humans about PEP effectiveness at various intervals after exposure. But I also am unaware of individual case reports of PEP failure when started 36-72 hr after exposure, so most likely it remains substantially effective. An important difference between the animal studies and the real-world experience may be the dose of virus during exposure: intentionally large in the animal models, to assure 100% infection in the untreated animals, and usually much smaller in most real-world situations. If PEP is more effective with small versus large exposures, which seems a reasonable possibility, there might be greater effectiveness than the animal studies documented.
I would encourage you to just follow the advice of your ID doctor, including discussion of these questions. Depending on his or her personal experience with PEP and HIV/AIDS management in general, s/he may be equally or more expert than we are on this forum.
I hope these comments are helpful. As implied above, I would be happy to comment further if you would like to say something about the nature of your potential HIV exposure.
HHH, MD
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47 months ago
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My exposure was at an Asian massage parlor and was intercourse with a condom it lasted for about 30 seconds. I know pep was absolutely not needed but I panicked and my anxiety got the best of me. I have never had any sexual encounter in 20 years besides my wife. We both have a very small sexual history. I tested for everything except HSV 1 and 2 and it was all negative at 6 weeks. However now I cant help but wonder if I could have possibly contracted HSV2. I had shaved my pubes a couple of hours before the encounter and there was skin to skin contact with my pubic area around the condom even though it was minimum it did happen. I have never tested for HSV1 but neither me or my wife has ever had a cold sore. I have had no signs of an outbreak of HSV2 and it has been 9 weeks.
1. Should I go get tested for HSV1 and 2 at Quest Labs? I believe it is an antibody test. I also realize this test is only about 92% accurate at 12 week according to Terry.
2. Could I test earlier than 12 weeks and still receive reliable results at 10 weeks or so?
3. I have also read about false positives on this test. Is that true?
4. Could pep have any affect on symptoms of HSV2 or testing?
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H. Hunter Handsfield, MD
47 months ago
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The chance of HSV after such an exposure, also considering your lack of symptoms to suggest HSV, isn't as low as that of HIV, but not far off. In addition, the negative HSV blood test results at 6 weeks argue against it: although it can take up to 12 weeks for detectable antibody, most new infections are followed by positive results within 6 weeks.
1) 92% sensitivity actually is good, and a negative result will not mean an 8% chance you have HSV2, but far lower. If we assume your prior probability of having HSV2 is, say, one chance in a thousand, then after a 90% sensitive test, there would be 1 chance in 10,000 you have it.
2) See comment above. But I don't think you should waste the money and emotional energy on this.
3) Yes. The HSV blood tests can be falsely positive. However, since you have already had a negative result, this isn't likely an issue for you.
4) There are no data on PEP interfering with the HSV antibody tests, but also no biological or physiologic reason to suspect such an issue.
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47 months ago
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Sorry you must have misunderstood my last reply. I have tested for everything except HSV1 and 2 at 6 weeks.
1. So I guess my question is should I take the test or try to move on with my life without it?
2. If so would a 10 week test be adequate?
3. Since I have not taken it is there is a real chance I could have a false positive?
4. I realize some people can go very long periods without a breakout. How likely would that be for 9 weeks after an exposure.
I apologize for some repeated questions I'm just worried.
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H. Hunter Handsfield, MD
47 months ago
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Yes, I did misunderstand: I guess I read your comments too quickly and thought you had already been tested. Sorry.
1) I strongly recommend against testing for HSV in this situation. Your risk is too low and the tests not good enough. There is a greater chance of false or misleading results than any chance you have herpes.
2) If you get tested, why not wait only another 2 weeks and reduce the chance of a false negative result? A negative result at 10 weeks would be less conclusive than at 12.
3) Several percent of uninfected persons have positive results for HSV2, but rarely for HSV1.
4) Probably around half of newly infected persons have no symptoms. However, probably many more (60%? 80%?) of anxious persons who are continually on the alert would notice symptoms. It's the unworried and unaware who are most likely to not notice symptoms of new herpes. So absence of symptoms for you is pretty good evidence, all by itself, that you weren't infected. And you had such a low risk event anyway!!! (When a female has HSV2, the risk to her uninfected partner is roughly once for every 1,000 episodes of unprotected vaginal sex. And you used a condom, markedly reducing that risk!
You really did have a very low risk exposure in regard to herpes. This really is a pretty irrational concern.
That concludes this thread. Best wishes, whatever you decide to do.
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