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DYING WITH ANXIETY - specific question about 4th generation combo

May 1, 2013

I want to thank you in advance. PLEASE HELP!!!! I've tried to call several different hiv hotline and have asked my doctor, and no one knows! Basically, my question is this :Would hiv p24 antigen most likely still be detectable at around 5-6 weeks post exposure? and if not, why is there an advantage to the 4th generation antigen/antibody combo at that specific point in time (around 5-6 weeks post exposure) over the 3rd generation antibody test? is there a point after the first few weeks after exposure where neither antigen or antiboy would be detectable or it is usually that at least one of them will be detectable if someone is hiv infected? I'm worried about the likelihood of a false negative as I only took this test once about 1-2 days short of 6 weeks post possible exposure. (it was neg) I know you're gonna say only 12 weeks is conclusive but please address my specific questions about probabilities. Thank you.

Response from Mr. Cordova

Hi there,

It is possible that the p24 antigen would be detectable at that point. Serum concentrations of p24 antigen are high in the first few weeks after infection; tests sensitive to p24 antigen are therefore useful for diagnosing very early infection when antibody levels are still low.

By week 5-6, p24 antigen levels have already dropped considerably, but the body has produced enough antibodies that can be detected by an antibody test. Most people will show up positive on an antibody test by 28 days, with all outliers by 90 days.

Between the antigen portion and the antibody portion, a person who is infected can find out their status early on in the infection, and then later at the standard testing windows of 28 days (preliminary) and 90 days (conclusive).

I hope this helps.

In health,


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