If they can come inside on your clothes, what stops them coming in during the six months they are not necessarily covered for? I would suggest having 6 monthly if you vaccinate at all, otherwise it's not complete peace of mind.
From my understanding the vaccination covers them for the whole year, but getting it every 6 months just means it's stronger which is better for bunnies in high risk areas. I may of course be wrong.
My outdoor bunnies are vaccinated every 6 months.