Does PEP Treatment Affect Previous HIV Infection Test Results?

Does taking PEP affect the results of previous infection assessments?

Hello doctor: My situation is as follows.
I had sexual intercourse with a person I met online (A) on September 15 and with another person (B) on September 26.
The sexual activities included anal intercourse with a condom and oral sex without a condom.
I was the insertive partner.
After the encounter with B, he informed me that he is HIV positive, but his recent tests over the past six months have shown an undetectable viral load.
Due to my panic, I sought PEP treatment on September 27, and I am currently on the fourth day of the regimen.
I would like to know if I can trust the results of an HIV rapid test on October 15 to confirm whether I was infected during the encounter with A on September 15.
Will starting PEP affect the reliability of the test results?

Xiao Gang, 20~29 year old female. Ask Date: 2020/09/30

Dr. Hong Yuanbin reply Internal Medicine

Hello, the reliability of the HIV rapid test report is high, and PEP should not affect the test results.
However, since there was still unsafe behavior on September 26, it is recommended to undergo another screening after October 26 for confirmation.
Thank you for your inquiry.

Reply Date: 2020/09/30

More Info

PEP, or post-exposure prophylaxis, is a critical intervention for individuals who may have been exposed to HIV. It involves taking antiretroviral medications within 72 hours after a potential exposure to HIV to reduce the risk of infection. Your question about whether PEP affects the results of previous HIV tests is quite pertinent, especially in the context of anxiety following potential exposure.

To address your concern directly: PEP does not affect the results of previous HIV tests. When you undergo an HIV test, the result reflects your HIV status at the time of the test. If you were HIV-negative before starting PEP, that status remains unchanged by the initiation of PEP. Therefore, if you take an HIV test after starting PEP, the result will indicate your status as of that test date, not your status prior to starting PEP.

In your specific case, since you had sexual encounters on September 15 and September 26, and you began PEP on September 27, the test you plan to take on October 15 will primarily reflect your HIV status as of that date. It is important to note that the window period for HIV tests can vary depending on the type of test used. For instance, an HIV antibody test may take longer to detect infection compared to an HIV RNA test (like PCR), which can detect the virus sooner.

Given that you had a potential exposure on September 15, it is advisable to wait at least 4 to 6 weeks after that exposure for the most accurate results, especially if you are using an antibody test. However, since you are on PEP, it is crucial to understand that while PEP is highly effective, it is not 100% guaranteed to prevent infection. Therefore, even if your test on October 15 is negative, it is recommended to follow up with additional testing at 3 months post-exposure to confirm your HIV status.

Moreover, the effectiveness of PEP is contingent upon adherence to the medication regimen. Missing doses can reduce its efficacy, so it's essential to take the medication as prescribed. If you experience any side effects or have concerns about the medication, you should consult your healthcare provider.

In summary, while PEP will not alter the results of previous HIV tests, it is vital to consider the timing of your testing in relation to potential exposures and the type of test being used. Regular follow-up testing after completing PEP is crucial for ensuring your ongoing health and peace of mind. If you have further questions or concerns, don't hesitate to reach out to your healthcare provider for personalized advice and support.

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