[Question #12531] 3rd generation HIV testing reliability

7 months ago

Dear Doctors... my HIV testing results came back NEGATIVE. It was a 3rd GENERATION antibody test. The test was taken 28 days after exposure. How reliable are the results of 3rd generation tests at 28 days? Thanks.

H. Hunter Handsfield, MD

7 months ago

Welcome back to the forum. Thank you for your continued confidence in our services and for your very succinct question.

The third generation HIV antibody tests detect 90-95% of infections at 28 days. It takes 8 weeks for a conclusively negative result. You could have a100% conclusive result at 45 days if you have an antigen-antibody (AgAb, 4th generation) blood test.

If you would like to describe the exposure you are concerned about, I could provide additional advice about the chance you were infected. But for now, you can safely assume you do not have HIV, even if you decide on retesting in 2-4 weeks.

HHH, MD

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7 months ago

Doctor… I’ve had sexual intercourse with a commercial sex worker half a dozen times WITHOUT protection. She said she was HIV negative. There were 2 occasions we had sex during her menstrual cycle and both times she was bleeding. Thanks.

H. Hunter Handsfield, MD

7 months ago

Most sex workers don't lie about HIV status when asked directly, so probably she isn't infected. Sex during menstruation does not make the risk any higher: the amount of HIV is about the same in vaginal fluids and blood. Your risk of HIV is low, but it's up to you whether to seek a more conclusive test -- either repeat 3rd generation at two months or AgAb test at 6 weeks or 45 days.

You might consider a urine test for gonorrhea and chlamydia; with condomless sex several times, these are far higher risk than HIV. Absence of symptoms (penile discharge, painful urination) is fairly good evidence you aren't infected, but still something to consider.

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