HIV 4th Generation testing is conclusive at 28 days (4 weeks). Even the docs here say it. It's not available be here because it's a new and very expensive test that can not be offered at clinics, only by you General Physician or Infectious Disease doctor. You won't find walk in clinics offering this kind of test (yet) in the United States for a while at least.
I know the New York State Department of Health is expecting an approval for the Determine Ab/Ag HIV 4th Generation Rapid test by the New Year for use in clinics and that's about it.
Dr. Handsfield explains it well but it basically can be summed up by saying that no one wants to be wrong. God forbid someone comes in saying they have a negative at 4 weeks using the DUO but then test positive at 12 weeks using the DUO, that would be quite a situation legally for the docs/educators who advised him he was completely 100% HIV free at 4 weeks.
It's hard to answer what's going on in the UK here from the US. My perspective here in the US is that the 4th Gen DUO rapid test doesn't seem to work as well as 3rd Generation Rapid test in terms of sensitivity and the 4th Generation testing by blood draw in a lab is, again, expensive, and not all labs are equipped with the Abbot Architect blood spinner which is the machine used for DUO testing to detect the P24 Anitgen.
Thank you for your very intelligent answer. Most hospitals in Britain do claim they use 4th Gen test. But many of of websites contradict each other (thus frightening people who were told their test was conclusive at 4 weeks.
I love America (I think it is the Greatest country in the world, but scientifically it can trail behind Europe and Asia (sometimes).
All the very best, Sharkboy67.
A paper published by the BCMJ-British Columbia Medical Journal in 2010 stated these window periods:
"20 to 22 days for third-generation enzyme immunoassay (EIA) tests, which detect HIV antibodies.
• 16 to 18 days for fourth-generation EIA tests, which detect p24 antigen and HIV antibodies."
What they are saying, is the average person who is infected with HIV would test positive in these time frames. The report also goes on to say a confirmatory test should be done at 3 months.
"Most patients can be tested at 6 weeks following a possible exposure to HIV, with testing repeated at 3 months if negative. We estimate >95% of individuals have detectable HIV antibodies by 4 to 6 weeks after infection (with >99% by 3 months). "
In respect to 4th Gen tests in the US. The CDC issued new guidelines 4 months ago stating this should included in initial HIV testing, and if negative no further testing would be required. If your doctor or lab is not providing them, refer them to the CDC website.
Thank you very much.
Proves my case if ask intelligent questions; you get intelligent answers.
All the very best.