Excellent field. It's a combination of healthcare and information technology (IT). BUT, if you're not already in healthcare or medicine, then it's tough trying to break into the field. There seems to be a preference for candidates who are already in medical/healthcare fields (doctors, nurses etc) who can be trained in IT instead of vice vesa.
If you're a youngin and in college, get your bachelors in a healthcare field (and possibly a minor in some type of computer related subject), and then do your masters in informatics. If you're already working in a healthcare field, then take some online classes in informatics.