From the Guidelines
No, if you have a negative 4th generation duo test and a negative qualitative RNA test at 83 days after exposure, and you completed PEP (Post-Exposure Prophylaxis), it is extremely unlikely that you would test positive at 90 days. PEP consists of a 28-day course of antiretroviral medications that must be started within 72 hours of potential HIV exposure, as recommended by the International Antiviral Society-USA panel 1. When taken correctly, PEP is highly effective at preventing HIV infection, with an estimated efficacy rate of 81% for zidovudine monoprophylaxis 1. The 4th generation test detects both HIV antibodies and p24 antigen, while the RNA test directly detects viral genetic material. These tests are conclusive by 45-90 days post-exposure. Having both tests negative at 83 days provides reliable evidence that infection did not occur, especially if PEP was completed as prescribed 1. The window period for HIV detection is shortened when antiretroviral medications like PEP are used, not extended, because they prevent the establishment of infection rather than merely delaying it. Some key points to consider:
- PEP should be continued for 28 days, and HIV serostatus should be reassessed 4 weeks to 6 weeks, 3 months, and 6 months after exposure 1
- Shorter serologic follow-up (eg, at 3 or 4 months) may be possible if using a fourth-generation assay 1
- The Centers for Disease Control and Prevention recommend TDF/emtricitabine plus twice-daily raltegravir or once-daily dolutegravir for postexposure prophylaxis 1
From the Research
HIV Test Results and PEP
- A negative 4th generation duo test and a negative qualitative RNA test at 83 days post-exposure do not necessarily guarantee that an individual is HIV-negative, especially if Post-Exposure Prophylaxis (PEP) was taken 2.
- PEP is highly effective in preventing HIV infection if taken promptly and adhered to as prescribed, but it is not 100% effective 3.
- The window period for HIV tests can vary, and it is possible for an individual to test negative at 83 days but positive at 90 days, even if PEP was taken 4.
Factors Affecting HIV Test Results
- Adherence to PEP is crucial in determining its effectiveness, and any deviation from the prescribed regimen can increase the risk of HIV infection 5.
- The type of HIV test used can also affect the results, with some tests being more sensitive than others 6.
- Individual factors, such as the presence of other infections or medical conditions, can also influence the accuracy of HIV test results 2.
PEP and HIV RNA
- PEP can suppress HIV RNA levels, making it undetectable in some individuals, even if they are infected 3.
- However, it is possible for HIV RNA levels to become detectable again after PEP is stopped, especially if the individual was infected before starting PEP 4.
- The relationship between PEP, HIV RNA, and test results is complex and requires careful consideration of various factors, including adherence, test sensitivity, and individual characteristics 6.