Dr H Hunter, I know your one of the best in your field! 7 weeks ago I had an incident where I got pricked by a drug needle at work (i work in a gym) and I'm worried I might of caught HIV! I went for a duo test at 4 weeks and 5 weeks and 5 days and both came back negative. My question in your opinion is that a conclusive result or should I be worried and to go back and repeat the test? I hear and read up about so many different opinions on the window period and really confused and why some say 4 or 6, 8, 12 weeks everyone different I've heard 4 weeks is 95%  but then I've read that you say it's 100%! I'm so confused! Also I've had herpes for 2 years and used to get a lot of recurrences like every 2-4 weeks, they put me on long term treatment for it  acyclovir 800 per day recently 1200 because my girlfriend is pregnant and I'm worried I could pass it to her! and with in the last 2-3,monthsI've had 2 outbreaks the last one being more than I usually get! Can that happen when on tablets? And can the acyclovir make the HIV test not reliable As it's an immune suppressant and may not pick up HIV abit like what pep does! I'm from the uk and really worried as my girlfriend pregnant! 

Welcome to our Forum.  Dr. Handsfield and I answer questions interchangeably and I happened to pick up your question today.  FYI, while our verbal styples tend to differ our perspectives on the facts and recommendations have not differed from one another in decades of working together.

I can understand why you find recommendations regarding when DUO tests provide definitive results confusing.  Different group approach the issue from different perspectives.  The companies which make the tests are only allowed to recommend the end points they used in their studies when seeking FDA approval for their tests.  Typically, the easiest path for these companies is to use the 3 month/12 week recommendation that their competitors have used in the past.  The CDC is a governmental agency and has to, in general, be conservative in their recommendations as well and, as a result, also tend to use conservative definitions.  In contrast, Dr. Handsfield and I, as well as other experts, based our recommendations on the published scientific studies that we read and hear about at meetings.  In the case of the DUO tests, study after study has indicated that results are reliable at any time more than 4 weeks after an exposure of concern.  It is these scientific data that we base our recommendations on and it is based on these data that I tell you that your results are definitive and you do not need more testing related to the exposures you have mentioned. 

As for your herpes, suppressive therapy markedly REDUCES, but does not eliminate recurrence, viral shedding and transmission to others. In your situation with a pregnant GF I would take extra steps and suggest the following:

1.  This is one of the places where a herpes blood test may be helpful.  Many people have HSV and do not know it and if she already has the infection, neither you nor she need to worry further about transmission.

2.  If she has not had HSV, in addition to the suppressive therapy you may want to consider using condoms for the duration of the pregnancy.  As I said above, while the risk of transmission is markedly reduced by suppressive therapy, it is not eliminated and you would not want to transmit infection to here and possibly your unborn child at this time. 

I hope this information and suggestions are helpful to you.  EWH

The effect of the acyclovir on your herpes tests is not the same as for PEP. Its a bit complicated.  Neither PEP nor acyclovir effect the immune system (i.e. they are not immunosuppressant), but directly effect the viruses involved.  With PEP people who are NOT infected are taking the medicine in an effort to avoid becoming infected.  Taking the medicine does not mask the infection but, because of the medicine's effect on the HIV virus, can delay the growth of the virus and therefore slow tests for HIV from becoming positive if the PEP fails.

Your situation is a bit different.  You have HSV and are taking the acyclovir to reduce the amount of virus present, thereby also reducing the frequency of recurrences and the likelihood of transmitting your infection to your GF who may be uninfected.  If you were to infect your GF, her immune system would not be effected and sighns of the infection would show up.

I know this is complicated.  I hope this explanation helps.  EWH

Yes, the performance of 4th generation or so-called DUO HIV tests is the same in the UK and US.  You can have complete confidence in your results at any time more than 4 weeks/28 days after your exposure.  You can be confident about your test results. 

It is difficult to judge the severity of your needle stick injury and now, at this time with negative test results, you need not worry further.  In the future, should you stick yourself with a used needle from an unknown person, or from someone who has HIV, you should seek post-exposure prophylaxis to prevent HIV.  Better yet, I hope you will be able to avoid such exposures in the furutre.

As per Forum Guidelines permitting  three responses per question, this will conclude this thread.  Take care.  EWH