The Hep B vaccine is generally very effective, but not everyone responds to it.
People in high risk occupations like health-care workers need to have a blood test after vaccination to see if it worked. Generally, an employer will inisit on seeing a certified postitive blood test result before they will offer a job.
If you have got satisfactory immunity to Hep B proven on blood test, then you are at an exceedingly low risk of contracting the disease.
Is this one of those things you can fight off? If not, it would kind of suck to catch it eating out becuase some place didn't wash their green onions well or something.
Hep B is mostly a disease that your body fights off in a few weeks-months (but it can make you pretty ill during that time). However, in about 1 in 10 people, it never gets fought off, and the virus persists, which can eventually cause cirrhosis of the liver and/or liver cancer. In the last few years, some partially effective treatments for persistant hep b have become available - but they are incredibly expensive, have lots of side effects and aren't always a cure - they just slow down the disease.
While Hep B is highly infectious (about 100x as infectious as HIV) it is generally only transmitted through blood (including childbirth, tatooing with unclean needles, drug abuse, etc.) or sexual contact. It is NOT passed on through food or water, on utensils, through the air, or through normal social contact.
isn't the immunization life lasting?
Generally, yes. Booster doses of vaccine are not recommended for people who have had the full course.
However, people at very high risk of catching the disease should have a blood test to confirm that they have got immunity.