They're all vampires, anyway

I was walking by this poster displaying many faces of various individuals, and I stopped to get a closer look. It turns out it was a Red Cross advertisment to promote blood donations. The caption above all the faces was "what do all these people have in common?" and below it read "their lives were all saved by people they will never meet." At first, I just took it at face value, but reading it again, it does sound kind of ominous for the donors... are they dead? Red Cross seems pretty sure that they will never get to meet the donors who saved them (yes, on the poster the word never was in italics). Does the Red Cross simply detain them or deport them to places they willbe unable to meet the donees? Or is it just a very extensive monitoring program, like teams of Red Cross vans that follow blood donors and if they get too close to a chance 'meeting' with a person they saved, they quickly intervene? So many unanswered questions from this seemingly simple poster... I guess the only way I'll figure them out is if I donate blood, then try to track down who my blood goes to, and then try and meet them.