Dr. HHH quotes "4 weeks isn't quite conclusive (about 98-99% reliable". Considering there is nothing called 100% in medical science, this is certainly is good enough for most people here with no to low risk. In fact, no expert online or I personally know quotes Duo to be 100% at 28 days, it is always between 94%-99%. Therefore, I don't see any change in the original information, I would still accept a duo conclusive at 4 weeks.