Hepatitis B Surface Antibody: What Test Results Mean

Created by: Tua Saude editing team
Key points
  • The hepatitis B surface antibody test checks whether you have immunity to hepatitis B from vaccination or a past infection.
  • An anti-HBs level of 10 mIU/mL or higher is generally considered protective after completing the hepatitis B vaccine series.
  • Other hepatitis B blood tests may be needed to tell whether immunity came from vaccination or a previous infection.

The hepatitis B surface antibody (anti-HBs) test checks whether a person has immunity to the hepatitis B virus (HBV). A positive hepatitis B surface antibody result may develop after vaccination or after recovery from a past infection.

The test is often interpreted with other hepatitis B blood tests, including HBsAg and total anti-HBc. Together, these results can help show whether a person has a current infection, a past infection, vaccine-related immunity, or no immunity.

The hepatitis B surface antibody test requires only a blood sample and usually does not require fasting or special preparation. In general, an anti-HBs level of 10 mIU/mL or higher after completion of the hepatitis B vaccine series is considered protective.

lab assay

What the test is for

The hepatitis B surface antibody test measures antibodies produced by the body against hepatitis B surface antigen (HBsAg), a protein found on the surface of the hepatitis B virus.

The anti-HBs test can help determine whether a person has developed immunity to hepatitis B. Anti-HBs antibodies may develop after successful hepatitis B vaccination or after recovery from a previous hepatitis B infection.

Other blood tests are needed to determine how immunity developed. In particular, total anti-HBc can help distinguish immunity from vaccination from immunity due to a previous infection, because people who have only been vaccinated do not develop anti-HBc antibodies. 

HBsAg test

While the anti-HBs test helps assess immunity to hepatitis B, the HBsAg test checks for hepatitis B surface antigen in the blood. A positive HBsAg result generally indicates a current hepatitis B infection, although it can temporarily be positive shortly after vaccination.

The HBsAg test may be ordered with anti-HBs and total anti-HBc to help determine whether a person has a current or past infection, immunity from vaccination, or is susceptible to hepatitis B.

If HBsAg is positive, a doctor may order additional tests to determine whether the infection is acute or chronic and whether treatment is needed.

How the test is performed

No fasting or other special preparation is usually needed for the hepatitis B surface antibody test. A small blood sample is collected and sent to a laboratory for testing.

At the laboratory, the blood is tested to detect and measure antibodies against hepatitis B surface antigen.

These antibodies can develop after recovery from a hepatitis B infection or after hepatitis B vaccination. Anti-HBs levels may decrease over time after vaccination, but most people who respond to the vaccine remain protected and can produce an immune response if exposed to HBV.

How to interpret results

The hepatitis B surface antibody result measures the amount of anti-HBs antibodies in the blood. Reference ranges can vary by laboratory, but results are generally interpreted as follows:

  • Anti-HBs below 10 mIU/mL: this is not considered a protective antibody response after completion of the hepatitis B vaccine series. Depending on vaccination history, risk factors, and other test results, a doctor may recommend vaccination, additional doses, or further testing.
  • Anti-HBs of 10 mIU/mL or higher: according to the CDC, this level is generally considered protective after completion of the hepatitis B vaccine series. Anti-HBs alone cannot show whether immunity came from vaccination or a past infection.

The doctor may also look at HBsAg and total anti-HBc to understand whether you have a current or past hepatitis B infection, or immunity from vaccination. In general, positive anti-HBc suggests a past infection, while negative anti-HBc with positive anti-HBs usually points to immunity from vaccination.

Update History
We regularly update our content with the latest scientific information to maintain an exceptional level of quality.

References
  • Conners EE, Panagiotakopoulos L, Hofmeister MG, et al. Screening and Testing for Hepatitis B Virus Infection: CDC Recommendations — United States, 2023. MMWR Recomm Rep. 2023;72(1):1-25.
  • Centers For Disease Control And Prevention. Hepatitis B. Ed.15 ed. : Public Health Foundation; 2026.
  • Centers for Disease Control and Prevention. Table 3-1. Interpretation of hepatitis B laboratory results. CDC. Accessed 21 Aug 2026 https://www.cdc.gov/hepatitis/hbv/interpretation-of-hepatitis-b-serologic-test-results.htm
  • JOOB, B.; WIWANITKIT, V. Anti HBs Assay for Post-Vaccination Seroepidemiology Monitoring: Diagnostic Concern. Clin Lab. 2023;69(11):.
  • JIANG, M.; et al. Anti-HBs levels in children under the age of two years born to HBV carrier mothers after immunoprophylaxis: a multicenter cross-sectional study. BMC Pediatr. 2021;21(1):492.
  • HUANG, S. W.; et al. Effect of Anti-HBs on Mortality Among Resolved HBV Infection: a Population-Based Prospective Cohort Study. Infect Dis Ther. 2023;12(3):871-890.
  • PONDÉ, R. A. A. Expression and detection of anti-HBs antibodies after hepatitis B virus infection or vaccination in the context of protective immunity. Arch Virol. 2019;164(11):2645-2658.