[Question #6738] Possible exposure and the new window period

13 months ago
Hello Doctor,
I was very happy with my negative hiv result on the 28th day until I saw the new window period on this forum.Here is my case.  I had an occupational exposure a month ago.  Around 1ul or less of blood went into my eye.  I washed my eyes within about 2 mins and both of the source patient and my blood were tested using 4th gen Abbott Architect and all came back negative.  I was then told by the occupational health department the exposure has no risk and no follow up needed.   However,  the patient expired a couple hours later due to terminal stage bone marrow cancer, sepsis and multi organ failure.  I've heard rare cases that patients have seroreversion at their end stages when they are no longer able to produce antibody.  

1) If that's true,  would p24 always be present?  Have you seen, heard any  or theoretically possible cases that both p24 and antibody remain undectable by 4th gen test especially terminally ill patients?

2) Should I have a retest at 6 weeks, or accept the negative result at 28 days and move on, or don't even have to get tested at all.

I also read the review article that CDC cited  regarding the new window period (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5718364/).   However, the data the original author used came from some old seroconversion panels sold by biocompanies.  It seems like the 99 percentile of the window period at 45 days was estimated based on statistical modeling of those seroconversion panels instead of recently reported cases (https://academic.oup.com/cid/article/64/1/53/2194435).  

 3) So, if my understanding is right, why do some experts and countries still recommend 28 days as the window period, since these seroconversion panels have been long existing for 20+ years and readily available on google.   It seems impossible  that they just realized they had been wrong for many years.

4)  How well do you think this study corrolates with the real world medical practice?

Thank you so much for your help

Respectfully



H. Hunter Handsfield, MD
H. Hunter Handsfield, MD
13 months ago
Welcome to the forum. Thanks for your quesiton.

The "new window period" isn't really new; no change in our advice for about two years. In any case, the "old" 28 day window still detects 98-99% of infections. And with the patient testing negative, I don't really understand why you're concerned. To my knowlege there have been no reported cases of HIV in healthcare workers from occupational exposure except by injury with contaminated sharp instruments; conjunctival exposure is one of those theoretical exposures with no proved cases of HIV transmission, whether in healthcare settings or personal (e.g. sexual) contact.

For those reasons, I agree with your occupational health department:  no risk at all. Once you knew the patient was HIV negative, I would have recomended against you being tested. To your specific questions.

1) "I've heard rare cases that patients have seroreversion at their end stages when they are no longer able to produce antibody." I am unaware of any credible scientific reports that this ever happens. I think you're reacting to an internet-based urban myth. If it happened, I'm confident p24 antigen would rise to high levels and the AgAb test would remain positive. 

2) As I said above, if I were in your situation, I would not have been tested at all. However, since you have started down that path, and given the heightened anxiety you obfiously are experiencing, you probably should be tested at 6 weeks. Many anxious persons are more reassured by negative test results than by professional opinion, no matter how expert and science-based.

3,4) The first of the two links you provide is the resource on which our advice on this forum is based. Why do some sources stick with 28 days? They are not wrong to do so. Of all HIV testing done, a small minority is in situations following a particular exposure. Most testing is done in people at general risk, without regard to a particular exposure event. In that context, a test with 98-99% sensitivity at 4 weeks, and virtually 100% at 6+ weeks, is entirely acceptable.

I'm not going to go further into a general discussion of HIV testing policicies and recommendations. Feel free to go ahead with another test at 6 weeks if another negative result will be reassuring. But really, this quite an overreaction to a documented zero risk situation, don't you think?

HHH, MD

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13 months ago
Thank you so much for your advice, and yes I also think this is an overreaction.  The reason behind this kind of overraction is that false positives occur quite often at our facility and they are usually resolved by repeating or confirming.  Although there's probably no documented false negative,  however, according to the current testing algorithm, the first negative result will be the final result.   I know it doesn't happen as often as false positive , but if a false negative trully happened, it will be mistakenly reported as a true negative.     This is the only reason why I chose to test myself at 28days but after reading your post, I dont't think I'm going for the 6 weeks test.
H. Hunter Handsfield, MD
H. Hunter Handsfield, MD
13 months ago
There are several reasons that false negative results don't occur, at least not with the combinations of tests you have had. As a scientist, I rely on data and am prepared to alter this perspective. But for now, while I understand the theoretical concern, I really don't believe it's a likely issue -- anywhere, any time.---
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