Dr. HHH, a question about 4th gen test

I did a 4th gen test P24 + Ag/Ab from Roche (Combi) about one year ago and the result was index 0.15 / cutoff 0.9 (negative). I did a second test 40 days ago and the result was index 0.38 / cutoff 0.9 also negative. This second test was exactly 29d after the sexual intercourse with a girl of unknown status. I used a condom for vaginal and anal penetration but had unprotected oral sex.

Questions:

Why this index change ? Any significant meaning ?
Is the last test conclusive at 29d ?

Thanks !

A bit anxious here

[Edward W Hook, MD]

Welcome to the Forum. I'll be happy to comment.  IFYI, I have read your earlier interactions on our community sites and agree with what you've been told there.  

Your results are conclusive.  Because the 4th generation tests test both for the virus (the antigen) and the host response to the virus (the antibody) they provide results far sooner than earlier tests which test only for antibodies.   You have indicated that you are already aware on our stance regarding the overly conservative recommendations which come from places subject to political influence such as the CDC.  You can have complete confidence in the test results that you have.

As for the chance in index, these tests report results out based on the results of the chemical tests used to perform the assays.  People and test performance vary day-to-day based on individual variation with time and other factors such as the test lot (the reactivity of chemicals can vary from lot to lot) and other factors such as room temperature or miniscule variation in the amount of serum (blood) tested.  A negative is a negative and that your negative values vary over time is of no meaningful consequence.

I hope my comments are helpful to you.  EWH

[CuriousAboutAll]

Thanks Doc. I´m calm now. Better to have my question answered by a M.D.

The excess of information and lack of knowledge is not a good comnination after all, you know. I was always bugged and in the lst 24hs I started to feel things that I rationalised before, and against all logic..

I was really curious about why the index variations. When I was at Univertity I did many analytical essays in chemistry, anf you know... having knowledge in some areas sometimes makes you to think by a wrong way in situations out of your knowledge domain.

If you say I´m ok after the 29d test, for me it´s final.

Thanks a lot. It really calms me now.

[Edward W Hook, MD]

Glad to help.  Take care.  EWH

[CuriousAboutAll]

Dr. Hook,

Please forgive the fact I addressed specifically to Dr. Handsfield, I didn't realize you shares this forum with him.

You're both doing a great work here, and I really appreciate.

=)

[CuriousAboutAll]

So, absolutely no way to have trouble after this test, right ?

[Edward W Hook, MD]

I should not need to repeat myself. Please see reply above and do not worry further.  EWH

[CuriousAboutAll]

Sorry. Tanks Again