testing for HIV...how accurate is it?

[itstallionman]

I have a friend that is HIV + and has been for many years, he told me that because of the meds that he has been taking his HIV test showed up neg. and undetectable.  Is this possible?  if it is then it puts a lot of doubt in my mind on the whole testing process.  When we get tested and come up Neg. are we really Neg.?  and the same goes for Pos. results.  How do we know for sure?  what testing procedure is most accurate?  If a person with HIV+ status gets a test that shows up Neg. can he/she still pass on the virus to others?  This was very confusing to me and makes me question the outcome of my own tests...If I tested pos. this time can it have been a mistake?  could I test neg. later?  am I really Pos.?  How accurate are these tests?

[Andy Velez]

It can happen in the very late stage of living with HIV that someone might test negative. I don't know where he is in relation to HIV. As for his being "undetectable," that is quite different than testing HIV negative. That's something that often happens with someone who is on HIV meds and is in fact a goal of going on to the meds. 

The standard ELISA HIV test is unquestionably reliable and has been proven so through years of use, as long as it is done at the proper time. The western blot is a highly sensitive backup test which is used to confirm an ELISA anytime there is a positive result.

If you haven't already the lesson on this site about Testing, I suggest you do so now. There's a link to it in the Welcome thread which opens this section.

 

 

[itstallionman]

Thanks Andy, So you are saying that an test that shows HIV as undetectable is (and shows) different than being Neg.?  A person who knows they are HIV+ for sure and has been on meds gets a test, it won't ever show as Neg. result but may show as undetable?  Well that kind of makes sense but isn't very reasuring as to the accuracy of testing.  if you don't know for sure and it shows up undetectable then you won't really know for sure if your Pos or Neg. right?  I have read the Testing lessons, I am not sure what test I have had it was just the basic blood test that they do initially for a regular check-up exam.

[Andy Velez]

No, you are still mixing things together.

Someone who is HIV+ and is not on meds is still going to test positive. Once someone has reliably tested positive they would presumably and hopefully be having regular checkups which would show where their viral load is at, which is a significant factor in determining if and when to start the meds.

As I said, sometimes in the endstage of living with HIV, someone could test negative. But that is quite different than undetectable, as I have previously differentiated.   

I don't understand why you are interpreting that to throw doubts on HIV testing in general nor how it relates to the recent blood test to which you refer. With the exception of that endstage possibility, if someone is HIV+ they will continue to test positive no matter what their viral load is.