Information about a laboratory test

Anti-HBs What Does This Test Mean?

Anti-HBs measures antibody to hepatitis B surface antigen in blood.

Test summary

Test name
Anti-HBs
Abbreviations
anti-HBs, HBsAb
Category
Infectious Disease / Hepatology
Panel
Hepatitis B Triple Panel
Specimen
Serum / plasma
Common units
mIU/mL, qualitative

What does the test measure?

Anti-HBs measures antibody to hepatitis B surface antigen in blood.

Why is the test ordered?

Anti-HBs is used to assess immunity to hepatitis B, especially together with HBsAg and anti-HBc.

Information about a low result

Negative/low anti-HBs alone does not define HBV infection status; vaccination history and other markers matter.

Information about a high result

Positive anti-HBs can be consistent with immunity after vaccination or past infection; interpretation depends on the other HBV markers.

Reference and clinical context

Start with the performing laboratory's reference or decision range, assay method, specimen and reporting unit. A single result usually does not establish a diagnosis on its own.

Reference context 1

>= 10 mIU/mL

Population
After complete HepB vaccine series
Specimen
Serum / plasma
Method
Serology

Sourced reference/decision context for Anti-HBs

This is sourced reference or clinical-context information; the user's own laboratory report, assay method and clinical context take priority.

Reference ranges may vary by laboratory, method used, age, sex, pregnancy status, and clinical context. The reference range on your own laboratory report takes precedence.

Interpretation notes

After a complete vaccine series, anti-HBs ≥10 mIU/mL is a known correlate of protection used by CDC; this threshold should not be applied without context.

Related specialties

  • Infectious Disease
  • Gastroenterology
  • Internal Medicine

Frequently asked questions

More information about this test

Sources

  1. Clinical Testing and Diagnosis for Hepatitis B — Centers for Disease Control and Prevention

    U.S. government clinical guidance · 2025 · HBsAg, anti-HBs, total anti-HBc triple-panel interpretation · Verified: Aug 12, 2026

  2. Screening and Testing for Hepatitis B Virus Infection: CDC Recommendations — United States, 2023 — Centers for Disease Control and Prevention

    U.S. government recommendation · 2023 · HBV triple-panel screening and post-vaccination anti-HBs protection context · Verified: Aug 12, 2026