Dr. Ko Wen-je claimed—I asked him this question—that it's done on an informal e-based system between doctors. In other words, if somebody's looking for something and says, I need this blood type, it's passed around through that. There are some fantastic dissident hackers who have wanted to hack into sort of a central database. We're not sure it exists.
On October 21st, 2014. See this statement in context.