Countries can heal very fast. However, when they are in their human disguises, they are more susceptible to injuries and even death.
But certain casualties can cause death, even without a human disguise. Like poison, illness, infections, child-birth, rapid gunfire, and exploding.
Meaning that they wouldn't die of natural causes or flesh-wounds unless something very drastic happens.
Whenever a country has scars, it is often assumed that it would've killed a regular person if given the chance.
