6 years ago i received the full dose of rabies the rabies post exposure vaccine for a possible exposure. how long does the vaccine last?

Check titer: If you have continued exposure, antibody titer can be checked and, intermittently, 1 cc. can be administered. For a single repeat exposure, two doses are given. The antibodies decrease over time. No one knows for sure how long the effect of the original vaccine will last.

Usually 2 yrs: The CDC recommends those in high risk professions that take this pre-exposure to have a booster at 2 yrs or have blood titers run to verify a level of protection. Six years is a bit long to depend on the last series. I would consult your doc about a booster if you have been exposed or need ongoing protection.