Vitality defines ones general health, whether it's their immune system, pain tolerance, or the toughness of the body. The lower ones Vitality, the lower their HP.

Your Vitality Skillscore is the amount of Hit Die you add to your maximum HP. Vitality may define your personal welfare, but if for example, someone else is in need of medical help: Vitality can be used to aid light wounds. It encapsulates both literal health, and the knowledge/skills that come with first-aid. A rarity in these days, as many people drop like flies.