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I received my vaccine years ago--am I still immune?

If it has been years since you have been vaccinated, you may need or may request an HBV surface antibody blood test to confirm that you are still protected. A person is considered protected if they have a positive anti-HBs or HBsAb test result greater than 10 mIU/mL. Sometimes these test results are under 10 and there is concern whether these low levels will still provide protection against HBV. Anti-HBs or HBsAb test results can decrease over time, but an individual can still be protected even if the test results are less than 10.

If your test results are low, your doctor may recommend a booster shot or a repeat of the series. If you confirm you completed the vaccine series, you can get a booster dose of the vaccine. Your surface antibody level will be tested again 1 or 2 months after the booster. If the blood test result is greater than 10, then you are protected and will not require an additional booster shot in the future. (Ongoing studies show continued immunity for 30 years) If a booster shot does not result in a level greater than 10, then complete the remaining two-doses of the vaccine series and recheck the levels again after 1-2 months. Retain a copy of the titer test as proof of immunity.


Find more Frequently Asked Questions here