Hi Sqad - I did this in the eighties.
Years ago there was in infectious window
which clearly they have been working hard to close with more and more sensitive tests - and I have to admit I dont know if it is closed. I dont think so.
The test I was thinking about was the viral load test - and that is taken as neg means neg. But of course we are talking about early infection.
It is a scientific hypothesis that can be tested - you can measure the seroconversion rate after transfusion
and the answer is here:
http://hivinsite.ucsf.edu/InSite?page=kb-07-02-09
three in 25 million units apparently
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