The authorities disagree about how likely Hep B infection through casual contact can be. The CDC pooh-poohs it, but some hospitals (e.g. Childrens in Philadelphia) say it's possible. And since the consequences are so horrible, my kids have the vaccine (my daughter is pretty safe, her patron saint is Maria Goretti, that'll give you an idea, but my son is JUST the sort of kid who would go get a tattoo at some fly-by-night parlour if a friend dared him . . . )
I think Hep B is the old Yellow Jaundice and if it is, then yes it is contagious...
I got YJ from drinking milk straight from a cow with YJ when I was 9...I was visiting some kids who lived way up in the back country...we caught the cow and milked her to put warm creamy (unsterilized) milk on our cereal...we took the bowls down to the cow...
The kids were healthy as horses and not effected by the cow..but the next week I was very sick and stayed home from school for 3 weeks,,,my brother caught YJ from me but a milder case...