I guess what I am not getting, and I would image others as well, is this, how are you going to get accurate data. I can only see a few methods.
Self disclosure - what is any different about self disclosure now, it is easy to lie and I don't see any incentive for someone to tell the truth if the would not in the current state of affairs.
Disclosure by sexual partners - even if you could get sexual partners to disclose this information, which you couldn't at a level to be effective, it still would not cover aspects such as IV drug use and potential job related exposures (unless companies were willing to face law suits for disclosing personal information).
Disclosure from medical professionals - Dr / patient privileged?!? Not to mention that still only covers medical status not activity - no different that have blood test results.
24th century big brother monitoring device - okay, back to reality now.
TO sum up why I (maybe others) think this idea is one for the junk pile:
Data - there is simply no method to collect data that is reliable enough for this system to be effective
Risk = status. That is a false statement. Someone can be in a high risk group and be clean or a low risk group and have HIV.
Why would I want to trust a system over my own methods of checking blood test, getting to know someone, and trusting my instincts about their truthfulness
In a room full of swingers - everyone is going to have a a crap score, because we sleep with multiple partners - unless they are newbies. So we are back to blood test, getting to know someone and using common sense
Further more, I don't think I would want a relationship with someone that put their stock in this system.
They have reduce me and my wife to a number - nice way to start a relationship. How about this, try getting to know me, ask for blood test results, engage in conversation, ask me questions, observe my behavior. Novel idea.
They are putting their trust in a system with so many inherent flaws as to be useless - if they are not being more careful than that, then they are too high a risk for me (kind of like the guy that says he can look at someone and tell if they are HIV positive - I would run away from them as fast as my legs could go)
And what about the idiot how looks at his great risk factor/credit score and decides he doesn't need to get regular blood test. Don't kid yourself into think that wouldn't happen. And he becomes a greater risk out of a false sense of security.
In theory a great idea, in practice it doesn't fly. SO far all I have seen from the proponents of this idea is how great it would be to have this system NOT how to address the specific problems of making it work.
Many great theoretical idea's never make it past the "you know what would be great" stage because they are impractical, I think this one falls into that category.