Hi I have a question concerning Duo Tests. I read on one of your posts that most experts consider these tests to be conclusive at 6 weeks. Would this time frame be for Antigen detection only or also Antibodies? Becuase other data states that antibodies can take up to 6 months to be detected. Can you please clarify which side of the test would be considered conclusive after 6 weeks, antigen, antibodies or both. Also after the disappearance of antigens how soon after does it usually take for antibodies to become detectable?
Thank-you for using AIDS Vancouver as your HIV/AIDS resource.
1.The DUO/4th Generation Test is a combination test that looks for the presence of both the antibodies and the p24 antigen. The DUO test is considered conclusive by many HIV specialists by 6 weeks. The antigen and antibody part of the test are not separated and given separate window periods. This test, all together is largely considered conclusive by 6 weeks. International testing standards will still encourage re-testing at 12 weeks (3 months).
2. The role of the P24 protein/antigen is largely to signal the body to create antibodies to fight an infection. Once the body’s antibody response takes over, the P24 levels drop and soon become undetectable. This is why the p24 antigen is detected only within the first couple weeks of exposure. So, the Antigen part of the test can detect the p24 protein immediately after HIV infection (first few weeks). On average, a person's body will create antibodies to fight an infection in 21-25 days. So, anytime after 4 weeks, if infected, the antibody portion of the test should be detectable. This means that by 6 weeks, the test would have either picked up the p24 Antigen from the first few weeks, or the Antibody from 4-6 weeks, giving an overall test accuracy of 99.9% after 6 weeks.
3. The window period for antibody-specific tests are 4 weeks to 3 months; the only reasons that antibodies may take up to 6 months to be detected are if the individual is undergoing PEP treatment, HCV treatment or has an immunodeficiency disorder. Other than that, everyone else can consider their HIV test results conclusive by CDC testing standards by 12 weeks (3 months). Older versions of the ELISA Antibody test (namely 1st and 2nd Generation) used to have a 6 month window period.
Hope this helps and please let us know if we can provide you with any more information.
Take care,
Stephanie
AIDS Vancouver Helpline Volunteer
email: helpline@aidsvancouver.org
Phone (Mon-Fri 9-4pm ): (604) 696-4666
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Hi,thanks for your
Hi,thanks for your information.I had sex with a sex worker 4 weeks ago and I used a condom and it didn't break or slip.but after 2 to 3 weeks some symptoms occured like a little pain in the left lymph gland of my neck and after it healed,I had sore throat for a few days.I also had a cold sore on my lip.I'm very scared.can I have HIV combi test after 4 weeks of that sexual activity?is the result accurate after 4 weeks?thanks very much.
Hi there & thanks for your
Hi there & thanks for your question.
First of all, I would like to note that having encounters with sex workers or erotic massage parlor workers do not necessary mean that she is more likely to have HIV or pass HIV to you. In fact, many sex workers are more aware of their status and get tested for STIs regularly to protect themselves and their clients. Activities (rather than people) are high risk. The two primary ways HIV is passed from person to person is through unprotected (vaginal or anal) sex or sharing needles.
In terms of your exposure, it is great to hear that you are using protection and getting tested regularly. If the condom did not fail in some way (break, tear, slip off) then it is extremely unlikely that you could have acquired HIV as HIV cannot get through condoms- no way, no how but at the end of the day, testing is the only way to know.
Your test results at 4 weeks are very accurate & a good indication of your status. I would recommend re-testing at 6 weeks with the HIV COMBI test as most HIV specialists will consider that test conclusive at that time. A negative result at 6 weeks is unlikely to change with further testing however official Canadian guidelines recommend re-testing at 12 weeks with an standard antibody test as COMBI tests are not regularly available and this older technology is recognized to have a 4-12 week window period.
Please let us know if we have not answered all of your questions or if you need more information.
All the best,
Monica
AIDS Vancouver Helpline
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