What would happen if a vaccinated dog bit you in the face real hard?

I have another dog, you see, I was playing happily with him and teasing him by removing his treat when he's just about to eat it. Then something happened, he got antsy and he just snapped like *click* that. he went wild then he jumped to my face and bit it really hard! He almost nipped my finger off too. I thought he was friendly for being called as a "companion" and being a puppy.