[Question #7674] Window period post exposure

54 months ago

Hello sorry to ask yet another question about window periods but with the recent change I’m confused and wonder how you guys would view my situation.

I had an exposure a little over a month ago (vaginal, condom breaking) and I am concerned about HIV because I got a call from the health department. I don’t know if it was my most recent exposure or from years ago.

Regardless I tested 12 days post exposure with the RNA test. Came out negative.

I then tested again two weeks after (4 weeks post exposure) with the 4th generation test. Came out negative.

Is a 6 week test the only conclusive negative or would a combination of a 12 day RNA accompanied with a 4 week 4th generation test also considered conclusive?

I’d prefer to not have to test again obviously but I’d rather be 100% conclusive. Thank you.

Edward W. Hook M.D.

54 months ago

Welcome to our firm and thanks for your question. Congratulations on your commitment to safe, condom protected sex. Unfortunately, uncommonly condoms do break (about 1% of the time). I u Virtue to continue that you were kind of use.

The manufacturers of HIVPCR tests state that the results are definitive at all times more than 11 days after exposure but it appears that a small proportion on positive tests may occur subsequently and, as a result many experts suggest follow up testing with a 4th generation tests. That said, there is almost no chance that you have acquired HIV from the exposure you describe. There are many reasons I say this. Let me list many of them:

1. You do not know that your partner had untreated HIV. HIV is relatively uncommon among U.S. heterosexuals, less than 1%.

2. Even if your partner had untreated HIV, on average infections occur once in every more than 2000 exposure (in other words, 99.9% of exposures do not lead to infection).

3. Although it is reported, I have never seen a case in which a person with a negative HIV PCR subsequently went on to become positive.

4. Likewise, we know that a 4th generation tests detect more than 99% of infections at four weeks.

Based on the combination of considerations listed above, I am confident that you have not acquired HIV from your exposure in which the condom failed, despite the fact that statistically there is a tiny chance (less than 1 in millions) that infection occurred. Were I you, I would have confidence that I was not infected and would not bother to test further. I hope that this perspective is helpful.

If any of my reasoning is unclear please use your up to two follow up questions for clarification. EWH

---

54 months ago

Thank you for your reply! I understand you personally would feel confident with the results but does the combination of these two tests have about the same conclusiveness as a 6 week test? I’m sorry for the insistence but I would just obviously hate to believe I’m negative just for my results to have changed. I know heterosexual sex is a low risk but considering I was told by the health department I feel I have good reason to think my partner could have been high risk.

I just want to know if my combination of tests and results were as close as possible to 100% conclusive. Thank you again.

Edward W. Hook M.D.

54 months ago

You are effectively asking if you add apples and oranges do you get apples. These tests are independent of each other. My assessment is that there is virtually no risk that you are going to develop a positive test related to the event you describe. By virtually I mean that your likelihood of testing positive is no higher than your risk of being struck by lightning while reading this. If this is not good enough for you, you should re- test with a 4th generation test at six weeks. EWH ---

54 months ago

Sorry for the bother. It’s just that other questions I saw you compare a combination pcr and 4th gen test at 4 weeks to the conclusiveness of a 6 week test. Plus the likelihood of my partners positivity. If the risk were a bit more exposure such as unprotected sex would you still consider my tests reassuring? I’m not sure how long the condom was broken.

All in all if you were in my position would you test again or recommend a patient to?

Also may I ask why the recommendation of testing changed from 4 to 6 weeks? Do a lot of people convert in that time period? Thank you.

54 months ago

I’m also concerned cause I have a tingling sensation on my pelvic bone although I don’t know if that is an ars symptom or not (I had surgery near there 2 years ago and that sensation has come and gone since then)

Edward W. Hook M.D.

54 months ago

I’m sorry you have not found my answer is helpful. Test performance is totally independent of the sort exposure which occurred. I have indicated that the likelihood that further testing will be positive Following your negative PCR test and your -4 week fourth generation test is measured as being less than one in millions of such situations I.e. chances are 99.9999% that your results are conclusive at this time). I would call this conclusive and would not test further. As I said earlier in this situation I would not test further.

The recommendations as to how long it takes for fourth generation HIV tests to be conclusive changed several years ago when the CDC heard reports of very, very rare instances in which person’s tests converted after four weeks. These events remain extraordinarily rare ( So rare that there are no scientific K-series reporting more than single instances of the sort of event but the CDC is a conservative organization which feels that it cannot afford to be incorrect.

I appreciate your anxiety over your possible exposure and having been notified by the health department of a possible exposure. I hope the information I have provided has been helpful. I am confident that you have not been infected by HIV through the exposure you described above. EWH

---

54 months ago

When you say test performance is independent of test exposure you mean to say that regardless of the exposure that occurred, no matter how high or low risk, the test results are still conclusive and accurate? Sorry that’s all.

Edward W. Hook M.D.

54 months ago

Correct. EWH ---

54 months ago

Thank you I was concerned maybe a higher risk would require 6 week testing but I appreciate the assurance that my RNA and 4 week test are conclusive regardless of what my risk was.

Thank you again.

Edward W. Hook M.D.

54 months ago

Thanks for your thanks. This completes this thread. EWH ---