Hepatitis B is spread through contact with infected body fluids. In Australia, it is quite common in the indigenous population, but not so common in the rest of the population.

My personal opinion is that it is not necessary for all babies at birth or later on, and you should feel happy declining it if that is your wish. Some midwives/doctors may be supportive, some may not - it's hard to predict. It's certainly not uncommon for people to decline it, though.

And, as mentioned, the Vitamin K is optional as well. You can have it as an oral dose, or alternatively, you can get homeopathic preparations that are high in vitamin K.