Is a 5th week HIV antigen and antibody test conclusive?

I had a high risk activity last August 19, 2010. The following are the results of my HIV tests:

September 2, 2010 (Day 14 or 2 weeks) HIV antibody 1 and 2 test: Negative
September 8, 2010 (Day 20 or 2 weeks and 6 days) HIV antibody 1 and 2 + p24 antigen test: Negative
September 22, 2010 (Day 34 or 4 weeks and 6 days) HIV antibody 1 and 2 test: Negative

I am planning to take an HIV antibody 1 and 2 test + p24 antigen or nucleic acid test on September 25, 2010. Is it conclusive or reliable to take this test at 5 weeks + 1 day?

or

Will I stop taking series of HIV tests already?

please help

[Vance2335]

We use CDC guidelines...3 month antibody test is conclusive.

[mike_no]

I would re-iterate what Vance said. But, since you mention that you had a "High risk exposure", I would recommend you to go for the Duo (p24 ag + ab) instead of NAAT at the fifth week. Also, try and take the test at the 6th week instead of the 5th as a 6 week negative on a duo changing ahead is very very unlikely.

The reason I suggest a duo over a NAAT in your case is further elaborated below:

a. If one has already seroconverted the 'Ab detection' of the test is active and still a  reliable result could be obtained (Usually,p24 ab could be detected from 5 - 14 days)

b. If the individual is seroconverting (it's rare at the 4th week,since the average time to seroconvert is 21 days) the 'Ag detection' of the test would be active and a reliable result could be still obtained.

P24 antigen is a protein which is found in one's body (assuming the person's HIV infected) at about 14 to 32 days after the infection, after the above mentioned time period detectable amount of AB would aways be present in one's body and the P24 Ag would not show up any more but the AB woul be detected. Hence, a P24 Ag and Ab 1& 2 test is advised at the 28th-42nd day for early detection.

For some one with a real risk, a negative at 28 - 42 days on a IV gen test would have been very indicative however it's warranted to be backed up with a final test at the 12th week wih a regular anti-body test.

[reallyregret]

Hi TheoRN,

To put it simply, the doctors in the doctor's forum advice that the ag/ab test, or the 4th gen test that you will be going for is near 100% reliable at 4 weeks or more.

That said, of course you will still need to go for your conclusive test at 3 months. But if you test negative for your ag/ab test at this time, you can very much expect your 3 months to be negative as well.


May God bless


reallyregret

[TheoRN]

Thank you for the information. I'll be taking the HIV antibody and antigen test (p24) on the 6th week, that will be on the 30th of September. I hope everything will be negative. I'm just glad that someone imparted sensible thoughts regarding my situation.

[Vance2335]

"I'm just glad that someone imparted sensible thoughts regarding my situation." Do not come here and throw insults around. I gave you advice based on the CDC recommendation, here in America. Mike_no and others have other tests available. The antigen test is approved for use in America but not a stand alone test for diagnostic purposes.

You don't even say what your high risk encounter was, so maybe you should have said that to begin with.

[anyoneasap]

Can a person have a duo test at 3 months for a conclusive result? or does the test have to be an antibody only test at 3 months for it to be conclusive?

[Vance2335]

Start a thread dedicated to your question and it will be answered.

[rubberball314]

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.

28 day onward testing negative is conclusive!!!!

Why tell people to go on stressing for 12 weeks that is outrageous!!!!

Your comments re the detectable P24 antigen the facts are that P24 test will pick up the antigen months after the infection timescale... why oh why is there such poor advise out here.

[rubberball314]

The uk is soon to reduce the conclusive time down form 12 weeks... this is about time as it is not warranted with 4th Gen tests... It is clear this is for company and license reasons not based on medical fact...

[Teak]

http://www.fda.gov/downloads/BiologicsBloodVaccines/BloodBloodProducts/ApprovedProducts/LicensedProductsBLAs/BloodDonorScreening/InfectiousDisease/UCM216314.pdf

Page 27
Current methods for the detection of HIV may not detect all infected individuals. An ARCHITECT HIV Ag/Ab Combo test result that is nonreactive does not exclude the possibility of exposure to or infection with HIV-1 and/or HIV-2. Nonreactive results in this assay for individuals with prior exposure to HIV-1 and/or HIV-2 may be due to antigen and antibody levels below the limit of detection of this assay.


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