I have noticed Dr Hunter and Dr Hook have acknowledged the rare occurrence of ‘second window period’. 

1) Has the CDC taken this into consideration before declaring the DUO test conclusive at 6 weeks?

2) Can the second window period possibly happen after 6 weeks? If yes, what is the probability.

I am worried about 2 exposures;

3) Hair cut injury on 29/08/2019 (had duo test 83 days after exposure) – I believe this is conclusive, right?

4) Lancet exposure on 27/08/2019 – (I had an INSTI hiv test at Freedom health clinic; I can recall the lancet is a pressure activated lancet but I can’t confirm if the doctor used a new one or not. 

I later had a duo test 54 days after exposure at Synlab.  Is this also conclusive? 

Lastly, what do you think about this study?

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4313264/

5) I noticed the patient’s date of exposure was not given at all. The writer only made reference to tests done after patient developed symptoms. It seems its only the Abbott architect test that exhibits the second window period. All other Duo test were reactive all through. Can we question the reliability of Abbott test rather than just acknowledge the existence of second window period?

I fully understand my risk are very low risk but an expert advise is needed for clarity sake

Thanks 

We have acknowledged that with the antigen-antibody (AgAb, "duo", "4th generation") HIV blood tests, some researchers believe a secondary window period is theoretically possible. Dr. Hook and I have never had such a patient and we are skeptical: to the extent secondary windows occur at all, they are very rare. Perhaps more important, the time frame of a theoretical secondary window with these tests is brief, a possible time after the test detects p24 antigen and before measurable amounts of antibody are present. This can only occur in the 2-5 week range. By 6 weeks, any slight chance of a secondary window is gone entirely. There has never been a proved case of newly acquired HIV that had a negative AgAb test 6 weeks or more after catching the virus, except rarely in people who were taking anti-HIV drugs during or soon after exposure (PEP, PrEP).

Those comments cover most of your specific questions, but to be explicit and assure no misunderstanding:

1,2) CDC has not changed its advice on this account because the theoretical secondary window is closed by 6 weeks. Jumping ahead to the research paper you cite, note that it described a secondary window that ended at 34 days, well before 6 weeks.

3,4) Those test results are conclusive in relation to the exposures described. In addition, they both sound like zero risk events. Nobody gets HIV in barbershops or from having blood specimens collected, whether by lancet or any other methods.

5) See comment above. I will also ask "So what?" That a particular test in an individual patients once in a long while gives a misleading result, it doesn't mean it is likely to ever happen again or to you. Worrying about such things is like trying to take precautions against being hit by a meteorite. The odds probably are about the same.  You really shouldn't be at all worried about the kinds of non-exposure events you describe or about how well HIV tests work. You're obviously not at risk.

I hope these comments are helpful. Let me know if anything isn't clear.

HHH, MD

Thanks Doc. Your write up is well understood.  

I think the research paper I cited actually described secondary window ended 34 days after the first test (Day 0); not exposure. 

The research paper explains that Day 0 viral load result is 2 million copies and duo test was reactive. 

This is the reason I faulted the study before the day of exposure was not given. 

I feel this research should not have seen the light of the day. It doesn’t seem logical enough. 

I understand CDC official statement supersede and a lot of work and analysis must have done before declaring 6 weeks conclusive. 

Do you also think 12 weeks for antibody test is a bit conservative? From your experience with patients, when do u think antibody test used today should be declared conclusive ( practically) 

 

Thanks 

The latest ("third generation") standalone antibody tests are generally conclusive by 8 weeks, even though official advice by CDC and others remains 12 weeks. Indeed that's a conservative stance -- overly conservative, in my opinion.

Last question. 

I notice you keep saying you are yet to see a 4weeks + duo test change. Is that still the case  for you and dr hook? 

That completes this thread. I hope the discussion has been helpful.