With a bit of luck it will be forgotten about. I'm imagining a very unpleasant conversation where you inform your dentist they could either scrub the instruments themself or hire a temp nurse to do this.
Weighing up the unbelievably tiny chance of you catching help b due to a work injury while having lower than recommended antibodies versus the unbelievably tiny chance your baby could be harmed by the booster. If you ask for risk assessment - it will never
be done within three months, would take teams of scientists three years. Impossible question? Delaying tactics will usually let you get what you want.
Although advice seems to be it's OK to get help b vaccine or booster while pregnant you could try delaying tactics (Could I have some time to think about it?) Or else give à statement that compelling you to have this while pregnant would affect your mental well-being. (This would certainly make me anxious - the younger the child the more vulnerable to everything.). They could either just chill out then let you get it when you return or else put you on plain dental nursing or reception duties only. (Only oral surgery and instrument reprocessing are considered high risk for sharps injuries).