yes a duo is a 4th generation test...ab/ag.
28 days for a duo is optimal
and is thr three week mark and good sign? or it changes often in future.
by duo u refer to elisa ag/ab antibody test. which is the fourth generation antobody test ?
a duo a 4 weeks or an antibody at 6 week will give you a very good indication of your status. at that point, it is HIGHLY unlikely that either will change when you test at the 3 month mark.