I found a lot of (sometimes confusing) info concerning window periods. I know most specialists consider the 12 week mark as conclusive, however in some cases 6 months is mentioned. When should a person consider a test after 6 months?
Thank you for your inquiry. From what we gather from the question, you were asking about the window period for a completely conclusive HIV test.
The difference between the two window periods you provided is due to the type and age of the test involved. Some of the older HIV tests were not as good at detecting very small amounts of HIV antibodies in the blood (i.e. a newly acquired HIV infection), making the window period for the test 6 months, which is much longer than it is now (1). The newer 3rd (antibody detection only) and 4th (antibody and antigen detection) generation HIV tests are much better at detecting very low amounts of HIV antibody/antigen in the blood. That is why the window period for a completely conclusive result from these newer tests is 3 months (~12 weeks). It is important to note that with the newest HIV test (4th Generation Ab/Ag "DUO" test), most HIV specialists agree that at 6 weeks the result of the test is conclusive due to the high sensitivity of the test.
Recommendation: Refer to a physician for more personalized answers.
AIDS Vancouver Helpline/Online, Marie