Wow, a ton of great ideas folks, thank you.  And thanks also for the words of encouragement.

Butcher - thanks for the sum up.  I'm not sure it exactly hits the nail on the head, but it sounds badass nonetheless!

Cylonophile - I agree with you that I totally want to distance myself from the zombie genre.  Frankly, when I wrote my premise and backstory, it never even occurred to me that other people might think this is a zombie game.  Yet, when I posted on another site (RPG Net--I hope that isn't a bad word here?), a ton of people kept bringing it up.  So perhaps I need to rework the story more to make it very clear that these creatures (and there will be many different types) are not zombies.  

One horse town - I will definitely be playing up the medical aspect.  For example, a large part of each encounter will involve the doctors using their special knowledge and skills to figure out what the hell they're dealing with before jumping into the fray...

EBM - I'm woefully uninformed about generic game systems, so perhaps I should check them out, particularly since it seems I may have underestimated the work I need to do...

Cranewings - thanks for the support and for the vote of confidence in the Nazi starting point...

I think the medical theme will also give you tons of cool layout concepts to work with here. My only caution is if you play this side up this side of the design, be careful not to lose your non doctor audience in the process by getting overly technical on them (unless it is fluff that doesn't require understanding). Also if this is the case, and the medical theme is a critical component, you will probably want to make sure that you have mechanics to match to meet your design goals. I think one thing reviewers will look for immediately in a game about doctors, is whether they can play a doctor effectively using the system.