Vaccine for hep b does it mean i woudnot never get the virus even if i exposed to it from patient with virus?is there also booster vaccine and when?

You need to get the: whole vaccine sequence in order to be protected. It has a series of 2 boosters in short sequence from the initial vaccine. Your body's immune system needs to recognize it, to react to it, and if you're missing the sequencing, then you're inadequately protected. It's not like tetanus shot, where you need a booster every 10 years. You just need to complete it once. Adolescent dosing is different.