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Hepatitis B Surface Antibody (HBsAb)

Published: July 27, 2026Updated: August 25, 2026

This biomarker measures the level of antibodies produced in response to the hepatitis B surface antigen, indicating immunity to hepatitis B virus.

Quick summary

HBsAb levels indicate immunity to hepatitis B virus.

Medically reviewed by WellAlly Editorial TeamLast reviewed August 25, 2026Editorial policy

Key facts at a glance

Units
mIU/mL
Clinical utility
diagnostic
Result kind
quantitative
FDA-cleared
Roche Anti-HBs, Abbott Anti-HBs, Siemens Anti-HBs
interpretation: {"text":"HBsAb levels >10 mIU/mL indicate immunity to hepatitis B, either from vaccination or past infection.","label":"Immune"}; {"text":"HBsAb levels <10 mIU/mL suggest no immunity; vaccination or booster may be recommended.","label":"Non-immune"}

Hepatitis B Surface Antibody (HBsAb) is a blood test that detects antibodies produced by the immune system in response to the hepatitis B surface antigen (HBsAg). It is used to determine if a person has developed immunity to the hepatitis B virus, either through vaccination or previous infection.

The reference range for HBsAb is typically between 10–10000 mIU/mL. Levels above 10 mIU/mL generally indicate immunity, while levels below this threshold may suggest a need for vaccination or a booster shot.

This test is crucial for diagnosing past exposure to hepatitis B, assessing the effectiveness of vaccination, and guiding clinical decisions regarding patient care and prevention strategies.

Frequently asked questions

What does a positive HBsAb test mean?
A positive HBsAb test indicates that you have antibodies against the hepatitis B virus, meaning you are immune to it, either from vaccination or past infection.
What if my HBsAb levels are low?
Low HBsAb levels (<10 mIU/mL) suggest you are not immune to hepatitis B and may need vaccination or a booster shot to achieve immunity.
  1. 1
    Mayo Clinic: Hepatitis B TestSource
  2. 2
    CDC: Hepatitis B VaccinationSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 25, 2026. · Read our editorial policy