My parnter is immune to hep b does that mean he was infected with the virus first and did he catch it threw unprotected sex?

Perhaps immunized!: Your partner may have immunity to Hepatitis B because of having been vaccinated. From your question, I am not sure if he is immune - or a carrier. If he has contracted Hep B, it may have come from sex with an infected partner, from a blood transfusion years ago, or from IV drug use. Ask him for more information. LGromkoMD

Details are everythi: The details of the blood test will identify those who are immune because of vaccination from those who are chronic carriers from those with acute infection. Interpretation is best discussed with a gastroenterologist or infectious disease DR and put into therapeutic perspective.

Infected or vaccine?: Probably your partner had a blood test showing antibody to the hepatitis B virus (HBV), i.e. anti-HBs and/or anti-HBc. It means one of two things: either he was vaccinated against hep B; or he was infected and his immune system cleared it up. The details (anti-HBs or HBc) can help tell. If he was infected, the blood test says nothing about how he caught it. If you feel you need to know, ask him!