1) I just want to know since you said it is “ usually unnecessary “, when is it necessary to do a PCR after a conclusive 6 week negative Ab/Ag test ? 

PCR testing has become more widely available and somewhat cheaper although PCR tests remain substantially more expensive than 4th generation tests.  OTOH, with more experience with currently available commercial PCR tests, the tests have become more reliable.  For that reason, in the past few months we have our advice on the reliability of PCR tests for HIV. At this time, we can say with confidence that HIV tests taken 11 or more days after an encounter of concern will provide reliable, conclusive results and we feel that there is little need to follow a negative HIV PCR test taken 11 or more days after exposure with 4th generation tests at 4-6 weeks.  We are unaware of persons with negative HIV PCR tests at or beyond 11 days who have gone on to develop positive tests.  They do remain more expensive than 4th generation tests (prices vary) which remain our preferred tests for HIV testing.  

2.  Dr. Handsfield may have been referring to the so called 'window period" which occurs rarely in which soon after infection there may be a brief time when both antigen and antibody assays are negative because antibodies which are beginning to be formed combine with all circulating p24 antigen.  This phenomenon is quite rare and tends to be brief.   So-called "elite controllers" who can be chronically infected with HIV but whose immune systems delay or keep the infection from progressing typically do have both positive 4th generation tests and positive PCR tests.

I may have said more than you needed in reply.  I hope that I have not confused you.  The bottom line however is that a 45 day combination HIV antigen/antibody test is absolutely conclusive and reliable and remains our preferred test for HIV

EWH

2.  I cannot comment on what Dr. Handsfield was saying and suspect you are misinterpreting what was said.  EWH

As I said above (twice- a 45 day 4th generation test is conclusive.  Asking this question repeatedly will not change the answer.  

I cannot comment on why Dr. Handsfield made the statement he made.  Again, it was nearly 3 years ago.  

This completes this thread.  Please have confidence that a 45 day 4th generation combination HIV antigen antibody test will provide entirely conclusive results.  EWH

“ Some sources have claimed that antigen may disappear before antibody has developed, in theory creating a "second window" of transiently negative test results. This is now known to never occur, or so rarely it can be ignored:“