I know that people always say that the window period is 3 months but I recently had a rapid test done at a clinic with fingerprick and it was negative. I was wondering how conclusive this test is at 6 weeks, 8 weeks etc? How does this. Compare to say a 3rd gen test done by a quest or labcorp? Have you seen a person negative via rapid at 6 weeks seroconvert later on?
Uncertainties about time to reliably positive HIV test results continue to be a dominant discussion point on this and MedHelp's other HIV forums. When an antibody-only test is done, 3 months is indeed the official time frame for deinitive results. However, all the standard antibody tests in current use reach positive results by 4 weeks in 90% of cases, and almost always -- if they're going to be positive at all -- by 6-8 weeks. The time is shorter -- about 4 weeks -- if antibody testing is combined with a test for HIV itself, either with p24 antigen (in the "duo" or "combi" tests, also called "4th generation" tests) or by adding a test for HIV DNA/RNA. The rapid antibody tests can be considered 3r generation; they become positive just as quickly as lab-based antibody tests by Labcorp, Quest, or most other laboratories.
The reasons the official time for definitive results -- by the test manufacturers as well as most public health agencies -- have to to with the methods used to determine test performance as well as the regulations of agencies like the US Food and Drug Administration. These issues are described in more detail in the thread below:
It really doesn't matter whether I have personally seen anyone whose antibody test was negative at 6 weeks and became positive later. As it happens, I have not -- but that doesn't mean it never occurs. But if it does, it is very, very rare.
I hope this has been helpful. Best wishes-- HHH, MD
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