According to CDC guidelines now a 4th generation hiv test is basically conclusive at 4 weeks. Appearance of p24 antigen at around 15 days peaking at 30 and a 3rd generation hiv test being able to detect igm antibodies at around 23 days (for both hiv1 and hiv2). I understand the p24 antigen is only related to detecting hiv1, and that the 4th generation test, as it pertains to antibody detection, works pretty much the same as 3rd generation. My question is, is the 4th week negative test post exposure enough to exclude hiv2? Are laboratory markers for hiv2 the same as hiv1? Is a 4th generation negavtive test done at 20, 26, 31, 47 and 71 days post exposure enough to exclude hiv1 AND hiv2 infection? I understand hiv2 is rare but regardless, it would seem appropiate to exclude it.