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Had unprotected sex. Got negative result for DNA PCR test and P24 antigen test. Any suggestion?

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General & Family Physician
Practicing since : 2009
Answered : 9400 Questions
Hi Doc ,
I am male 40 yrs at India . I had protected vaginal sex but unprotected insertive fellatio ( 2 mins ) with a call girl . On the 11th day and 18th day after exposure went for both DNA PCR test and P24 antigen test and all the 4 tests turned out to be negative.
Please appraise me about my current status and shud I consider the results to be conclusive . Please let me know wether I shud go for any more tests . If yes , which test and at what time frame .
I somehow managed to avoid any sexual contacts with my wife. Looking forward to your kind reply and I am under lot of stress and guilt
Posted Wed, 24 Apr 2013 in HIV and AIDS
Answered by Dr. Shoaib Khan 1 hour later
Hello and welcome to XXXXXXX

Thank you for writing to us.

A HIV PCR test is considered quite specific and sensitive. It is usually used for early detection of HIV. The test can be conducted 2-3 weeks after contact with a HIV-infected person. Although you have undergone this test at the 11th and 18th day post-exposure, there could still be a possibility of a false-negative result due to an early test, as different people have a different immune response. I hope this is clear. Thus, the PCR could be repeated after 3 weeks of exposure (but only till 4 weeks since exposure, after 4 weeks, this test will be ineffective).

A P24 antigen test is only conducted to rule out false-negative reports during the window period, these need not be done to report your HIV status.

But, for your complete satisfaction if you wish to get tested again, the only test you could go about after this duration (i.e after 4 weeks) is an antibody test.The best time for an antibody test is from 3-6 months after exposure. An antibody test is highly sensitive. And if you wish to go about this, please get tested at 3 months and 6 months after exposure. I understand it can be difficult to keep away from your wife sexually for this long, but this is in her best interest.

I hope you understand. As far as the tests already conducted go, your negative status is almost 50% confirmed. We can only confirm it completely once the tests are done at the right time frame.

I hope you found my response helpful and informative. Do write back to me for any further clarifications, I would be happy to help.

Best wishes.
Above answer was peer-reviewed by
Follow-up: Had unprotected sex. Got negative result for DNA PCR test and P24 antigen test. Any suggestion? 17 hours later
I had protected vaginal sex but unprotected oral sex ie insertive fellatio ( 2 mins )

what is the risk of getting HIV transmitted do i stand if i assume the call girl is having HIV or recently infected with HIV .
Answered by Dr. Shoaib Khan 6 hours later
Hello once again.

Although the risk of transmission of HIV by receiving oral sex (i.e. insertive fellatio) from a HIV infected person is extremely low, yet it is still present, thus highly unlikely, but still possible.

I hope this information helps. DO write back to me for any further clarifications. I wish you a safe and disease free life.

Best wishes.
Above answer was peer-reviewed by
Follow-up: Had unprotected sex. Got negative result for DNA PCR test and P24 antigen test. Any suggestion? 47 hours later
Hi Doc ,

Now i am on my 32nd day of exposure . Shud i go for a test . If Yes , then which test
Else Shud i go for after 12 weeks . But that would be a long time to bear the stress .
Are there no test which can confirm my status at 42nd day .

Besides the same , as i have read , the DNA PCR TEST gives 99.6% accurate reasults at 2 - 3 weeks so i did the test and the SRL Religare manager told me the same .

Also can refer me a doc at kolkata

Please help .

Answered by Dr. Shoaib Khan 1 hour later
Hello once again.

As mentioned by you, you are now at 32 days post exposure. At this time, the best test to detect your HIV status would be a HIV DUO test. This test combines an antibody test for the HIV 1 & 2 strains of the virus with an antigen test for the p24 antigen. This test is your best option now, as it is considered 99.8 % accurate after 28 days. This accuracy goes up to 99.9 % by 9 months.

So, you could go about this test, and confirm your status.

Yes, you are correct about the DNA PCR accuracy, but it is most accurate after 21 days of exposure. Thus, I had asked you to get tested again.

From the information I have, I have heard that Dr. XXXXXXX Tiwary based in Kaikhali, Kolkata is a good HIV specialist. Although I do not know him personally, and thus do not have his personal contact number, but you can try the link provided below:
I hope this information helps. I wish you lots of luck my friend. Be safe and happy always.

Best wishes.
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