Does auras work on mercs?

Couldn't find any information about this. Merc counts as an ally, so aura should work on them. But, when I turned on Vitality aura and checked my merc stats, his regeneration didn't change. How it works? Is there any other way to make merc stronger except of giving to him gear?

EDIT: I checked again, auras work on merc. Idk why it didn't work in first time, probably because I did it in hideout.