[Question #6662] Rapid test window period
64 months ago
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Dear docs,
sorry if my English isn’t perfect, I’m writing you from Italy, after unprotected vaginal exposure I took a rapid hiv antibody test approved in Europe at about 11 weeks after the exposure, exactly 75days. The test manufacturer says the conclusive results are after 12 weeks. Can I consider my negative test conclusive after 75 days or is too early? Here is the link to the mentioned test:
Regards
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H. Hunter Handsfield, MD
64 months ago
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Welcome to the forum. Thank you for your confidence in our services.
I am not personally familiar with this test, but presumably it is a modern antibody test (i.e. 3rd generation) or perhaps an antigen-antibody test (AgAb, i.e. 4th generation). All AgAb tests are conclusive any time after 6 weeks, and most or all 3rd generation antibody tests by about 8 weeks, and most people have positive results by 4-6 weeks. Therefore, I would consider your result conclusive. I see the manufacturer states 3 months, but that probably is conservative..
Even if not quite conclusvive at 75 days, you should be satisfied with the result and confident you didn't catch HIV. The infection risk from a single episode of unprotected vaginal sex with an HIV infected women averages about 1 in 2,500; and probably you don't know your partner is infected, so your risk probably is even lower. So even if we consider your result to be maybe ~99% conclusive, the chance you have HIV almost cxertainly is well under 1 in a million. However, if you feel you need 100% certainty from the test itself, it would be reaasonable to have another test a full 3 months (90 days) after the exposure. But stay relaxed in the meantime: almost certainly you don't have HIV.
I hope these comments are helpful. Let me know if anything isn't clear.
HHH, MD
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64 months ago
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Thanks for your clarifications, I’ve seen that the test is the European version of the clear view test sold in US. Same principles
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H. Hunter Handsfield, MD
64 months ago
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ClearView is estimated to detect 99% of infections by 58 days. It's safe to assume it detects all infections by 75 days.---
64 months ago
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Thanks, the test is a 3rd generation one then as you stated multiple times in your previous forum too the negative results after the 8th week should be conclusive. For peace of mind(I hope) I will test again after 12 weeks but I think I can hope that everything’s fine
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H. Hunter Handsfield, MD
64 months ago
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All data on test performance are "soft": the power of statistics to prove 100% test sensitivity at various times is limited. (There are no studies of the thousands of cases that would require, and most test data are estimates on the basis of only a few hundred patients at best.) In other words, all cited data are a combination of rough statistics plus expert opinion based on the known biology of HIV, antibody production, etc. As for Clearview performance, 8 weeks is 56 days, consistent with my comment above about 99% reliability by 58 days. Don't split hairs between 99% and "conclusive". Feel free to test again if you wish, but my guess is that there has never been anyone who tested negative at 75 days with a 3rd generation test and turned out to have HIV, with a positive later test. You won't be the first -- do your best not to worry.
That completes the two follow-up exchanges included with each question and so ends this thread. I hope the discussion has been helpful. Bet wishes and stay safe.
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