P24 Antigen + Antibody test

hi

All this info is upto date and is from the UK leading HIV source

HIV 1 and 2 antibodies and p24 antigen test (HIV DUO or HIV Combi test)

This HIV test is licensed in the EU for use after 28 days after a possible exposure. It is probably much better than this and will probably identify the majority of newly infected HIV positive individuals at between 14 and 21 days. This HIV test is referred to as a fourth generation HIV test. Certainly in our clinic we have had many new diagnoses of patients using this HIV DUO test combination in that time frame.

The HIV DUO test relies on the principle that when HIV first establishes itself in the body it will start to replicate rapidly and almost as a by-product of this replication a core protein - the HIV p24 antigen - is produced in huge amounts from around 10 days or so after first infection and before or during the time when antibodies to HIV are being formed. The p24 antigen will then stay at a very high level for the first few months after infection and later decline in line with the decline in HIV viral load as referred to above. It will though never completely disappear and will run a variable course of detection through the rest of the illness.

So in general, p24 antigen is formed slightly before antibodies are forming allowing us to close the gap between infection to detection time - the HIV window period. As time goes on, then the majority of newly infected HIV positive people will form antibodies to HIV 1 or 2 by 28 days. In combination then, looking for both the HIV 1 p24 antigen and also HIV 1 and 2 antibodies will allow for much earlier detection of HIV than looking for HIV antibodies alone.

28day onwards up to 90 days testing that produces a negative is 99.98% accurate.....

And the result doesnt change after that the 28 days it remains negative as long as there is no further exposure during that time.

The Uk is reviewing the conclusive time which is set at 12 weeks this is purley for license and manufacture issues

[Teak]

You're information is incorrect.

UK testing guidelines.
Post-test discussion

The need for a repeat HIV test if still within the window period after a specific exposure should be discussed. Although fourth generation tests shorten the time from exposure to seroconversion a repeat test at three months is still recommended to definitively exclude HIV infection.

http://www.bhiva.org/documents/Guidelines/Testing/GlinesHIVTest08.pdf