Personally I would only feel comfortable with asking about b, definately not a.

Vaccination is an extremely personal and private matter. And I dont think it fair to ask someone to put aside their beliefs and point of view to settle your own worries. I would on the other hand, stress that I would not want anyone to coming in contact into either bub or mum and dad, or anyone other primary carer for the bub, if they are sick, have been sick recently, or being in contact with sick people.