What is hepatitis b surface antigen in general?

Infection is active: If you are surface antigen postive = protein on the surface of the virus is in its active form which is still floating in your blood and indicates active/on going infectious state. This protein triggers body to produce antibody which can help rid off the infection or preventing it as in case of hepb vaccines. In your case, no antibody or not enough to rid of the antigen. Consult doc. Good luck.