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Dr. Andrew Rynne
MD
Dr. Andrew Rynne

Family Physician

Exp 50 years

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Suggest Tests To Confirm STD's

I had protected anal sex with a girl in Thailand and condom broke for second and I notced it immediatly, I did P24 combo test 13 days later and was negative and repeated it 25 days later and was negative again, is there still a chance that I am positive, I feel a swollen left cheek and this is scaring me, today is 26 days after incident
Mon, 10 Nov 2014
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Dermatologist 's  Response
Hello. Thanks for writing to us at healthcaremagic

P24 is an HIV derived antigen. Usually antigens become detectable in blood earlier as compared to antibodies, which may not be detectable for as long as 1 month and in some cases for as long as 3 months.
"P24 combo" uses both antigen and antibody detection. Therefore it can detect an HIV infection much earlier than an antibody based test.
The sensitivity of this test for detection of HIV is 99.8% at 28 days. A negative test result at 25 days after a risky sexual contact almost rules out HIV but I would suggest that you still retest after a week.

Regards
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Suggest Tests To Confirm STD's

Hello. Thanks for writing to us at healthcaremagic P24 is an HIV derived antigen. Usually antigens become detectable in blood earlier as compared to antibodies, which may not be detectable for as long as 1 month and in some cases for as long as 3 months. P24 combo uses both antigen and antibody detection. Therefore it can detect an HIV infection much earlier than an antibody based test. The sensitivity of this test for detection of HIV is 99.8% at 28 days. A negative test result at 25 days after a risky sexual contact almost rules out HIV but I would suggest that you still retest after a week. Regards