The Arcanians have healers in the classic magical D&D Cleric. Diseases simply will never have a time to get a foothold before it's eradicated.
And the psychic healers of Sharona, while not a efficient, still can make the infected victim cure themselves. Basically the "Promote self healing" their healers do sounds a lot like vaccines.
I agree with you wholeheartedly. Unfortunately, it's not the capacity to cure a disease that matters in a pandemic. It's whether or not the disease can be nipped in the bud before it overwhelms the available medical resources. If that happens people literally begin dying in the streets and mortality shoots WAY up.
This is the second time I've tried to write this, suffice to say the following are but a tiny few of a HUGE number of reasons why both sides could ignore a disease long enough for it to become an enormous problem:
- All the same reasons belligerents in the First World War had to ignore sick soldiers.
- Neither side seems to actually HAVE vaccines.
- Arcanian generals have to choose between healthy soldiers and ammunition.
- Arcanian soldiers can be re-infected.
- Healers and Clerics can be killed or fall sick themselves.
- Healers can't heal 100 people at once.
- Continuous universal prophylaxis is absurdly resource-intensive and impractical in this case. (Could someone with knowledge re: British Empire, malaria, and quinine weigh in?)
- Both sides can create passive carriers and super-bugs via improved healing and antigenic shift.
- Even lining people up and instantly healing them every day takes them out of action for a while.
- See: "CGP Grey" "Americapox"