Quote:

... i think it was 2 different forms of IDS.


I think Melissa is right.

But, remember that there is more than one "strain" of HIV. I vaguely recall seeing a diagram of the 50+ identified "strains" that divided them into two main groups.

Also, I'm not sure that modern tests are sensitive to all known strains. The strains used to appear in distinct geographic areas so this wasn't/isn't viewed as a problem: it wasn't crucial to test in LA for a strain only seen in Africa. This might not be true any more.

So, at least several years ago, if you wanted to be sure that someone was free of every strain of HIV known you needed more than one test. I assume they needed only one blood sample and the extra work was only in the lab.
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