I'm not sure if you are still tinkering with this mod or not, but here some things that I've noticed:
When dupes stress vomit, they are not exposed to germs.
When dupes pee their pants, they are not exposed to germs. (this is an exploit, as it means it's cleaner for them to pee their pants than to have outhouses or lavatories)
When dupes walk through (get wet feet from) infected water or are completely submerged (soaking wet from) infected water, they are not exposed to germs
When a sick dupe coughs on another dupe, the recipient is not exposed to germs, the buildings there are not exposed to germs, and the air there is not filled with germs.
I'm not sure if you are still tinkering with this mod or not, but here some things that I've noticed: