Good morning I read many answers in HIV HELP LINE however one of your volunteers has given inconsistent and erroneous answers that are consistent with the responses of the other volunteers. While everyone indicates that the window period is 12 weeks (84 days) Mr. Trevor indicates that they are 90 and he has answered many that if they have taken the test at 84 they should do it again after 90 days. He also replied that the elisa of 4 generation is not a duo test. So, the question is because someone from your volunteer community called "Trevor" responds differently to all the rest ????
Hello and thank you for contacting us.
It sounds like you are seeking clarity on the window periods for HIV testing, as well as whether the fourth generation test is a duo or combination test.
Fourth generation ELISA tests can detect both the p24 antigen and anti-HIV antibodies. This is why they are referred to as combo or duo tests. Third generation ELISA tests can only detect antibodies.
Tests that detect the p24 antigen (fourth generation) generally have shorter window periods than tests that only detect antibodies (third generation). This is because most people have detectable levels of p24 antigen by 20 days after infection, which is generally earlier than antibodies can be detected.
According to the Canadian AIDS Treatment and Information Exchange:
Fourth-generation HIV tests can detect HIV infection in 50% of people by 18 days after infection; 95% of people by 34 days after infection; and 99% of people by one and a half months after infection. (1)
Third-generation HIV tests are antibody-only laboratory screening tests. Third-generation tests can detect HIV infection in 50% of people by 22 days after infection; 95% of people by 40 days after infection; and 99% of people by three months after infection (1)
I hope this clears up some of your confusion on this subject.
Regards, AIDS Vancouver Helpline Volunteer, Dyson