Dear Dr. Bob,

Firstly may I take this chance to thank you for your efforts on this wonderful forum, providing quality real world advise to so many people.

My question is this, I tested HIV negative 9 weeks after a possible heterosexual exposure in a low prevelance area of Western Europe (vaginal sex lasting c. 2 minutes with a woman of unknown status I had met on vacation). I myself am a 34 year old UK male.

For personal reasons, I am unable to test on the NHS (my mother works at the local doctors surgery and tends to see all of my test results before I do). For this reason I was tested in a private clinic in a different city. The test I took was a 'rapid HIV antibody test', involving a pin prick to the finger, collecting blood in a tube and then applying it to a slide a bit like a pregnancy test. The resulting single line 15 minutes later showing that I was negative.

I am on a low income, and saving up to take this test was difficult. I decided to wait for 9 weeks as another net based forum (also chaired by a world respected HIV expert), suggested that essentially all exposures would be detected at 2 months.

Having come across this forum I am now wondering if I have potentially wasted my money, as you recomend a 12 week test rather than the 9 weeks test I took.

In your view, what percentage of true positives would be picked up by an antibody test at 9 weeks? Judging by the sensitivity and specificity of the test, as described by the nurse (not to mention the cost), I think it's pretty modern.

As I said, I'm on a pretty low income, but I promise you that a donation of as much as I can afford will be on it's way to your foundation.

Kindest regards.

Hello,

It is true the vast majority of HIV-infected individuals will have detectable levels of anti-HIV antibody in their blood by six weeks. However, in my opinion and that of many others, "vast majority" is probably not good enough when dealing with an illness like HIV/AIDS and the potential catastrophic consequences of missing an infection due to delayed antibody production. Consequently most published guidelines still recommend HIV-antibody tests be performed at least three months from the time of the last potential exposure. You can read more about this topic in the chapter on "HIV Testing Basics," which can be accessed under "Quick Links" on The Body's homepage.

I have no way of knowing which "rapid HIV antibody test" you actually took, nor can I provide you with accurate statistics about percentage of true positives detected by your specific test at nine weeks as that data does not exist.

Dr. Bob