Question

how does HBV prevented

Answer 1

Hepatitis B vaccine. The hepatitis Bvaccine is the most effective way toprevent infection. The vaccine is up to 95% effective against hepatitis B if you receive all the shots in the vaccination series (3 or 4 shots given at different times). The vaccine provides protection against infection for at least 20 years.
hope it helps you

Answer 2

I think it is HIV.
So to prevent HIV :
1) avoid using contaminated razors
2) avoid using injected syringe
3)avoid doing excess sexual relationship with many.
The main thing is from your childhood you have to take vaccination.