« Go Back

Accuracy of 4th Generation HIV Test


I take Humira for my psoriasis, does this affect the window period for hiv? I have tested using 4th gen tests at 19, 43, 76, and 144 days all were negative. Do I need to test again at 6 months?

Kind regards


Hello and thank you for your question.

We understand that you are wondering about the accuracy of multiple negative HIV test results you have received, as well as whether your test results could be affected by your psoriasis medication.

HIV antibody tests are not affected by other circumstances. This includes infections, medications, vaccinations, putting on weight, eating or drinking anything before the test, use of alcohol or recreational drugs, mouthwash or time of day. (1) Taking Humira will not affect your HIV test results.

4th Generation EIA (aka DUO or COMBO or ab/ag ) tests can detect both the p24 antigen and anti-HIV antibodies. These 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. 4th generation HIV tests have a sensitivity of about 99.9%. In other words, if 1000 HIV-positive people were tested for HIV, 999 would test positive and one would incorrectly test negative. Since the vast majority of people who get tested for HIV are actually HIV negative, the chance of a negative result being false is extremely low. (2)

Based on the timeline you have provided here, at least two of your HIV tests were performed past the one and a half month mark. Official HIV testing guidelines still recommend re-testing at 12 weeks for completely conclusive results. Your most recent test result performed at 144 days exceeds the 12 week mark, so you can consider your results to be conclusive. No further testing is required.

Regards, AIDS Vancouver Helpline Volunteer, Dyson