Many are asking, how secure will my data be? Will hackers be able to access it. Well, who knows? Many of us do online banking, and have trust in this process. With my back account, I know every crook around the word would see me as a target. Money has universal value. With my healthcare data however, I doubt someone on the other side of the world would be interested.
The only people that really might have an interest in my health data would be my family, friends, neighbors or co-workers. One can argue that my employer may as well. The real fear however would be if the government or insurance companies get access to my PHR data. If thats the case, they would not do it illegally by hacking (as would a neighbor). I'm afraid this would only happen if we allow a shift in public policy to take place which would permit our PHR data to be accessed by these other entities.
Once there is a sizable PHR database based on our nations population, it will be too tempting for politicians and policy makers not to try to make arguements to justify use of this data for the "public good". As politicians frequently do, they'll say, "we're doing it for the children".
This is the real threat to the privacy of our data.