Hepatitis B

Serology Interpretation

• Note: If only anti-HBc is positive (with negative HBsAg and HBsAb), consider:

  • Previous resolved infection with low-level anti-HBs not detectable

  • Occult HBV infection (check HBV DNA)

  • False-positive result

  • Resolving acute infection where HBsAg has become negative and HBsAb not yet appeared

Non-Responder

• Definition:

  • No current chronic Hep B infection

  • History of age-appropriate Hep B vaccinations

  • HBsAb <10 mIU/mL indicates lack of protective antibodies

• Management:

  • Booster (4th dose) → retest HBsAb in ~4–5 weeks

  • If still negative, give an additional 2 doses (1 month apart) → retest 4 weeks after final dose (total 3 extra doses)

  • Persistent non-responders: If exposed to HBV, require HBIG (Hepatitis B Immunoglobulin) within 72 hours for immediate passive protection

Testing for Hepatitis B

Serological Testing

• Determines acute/chronic infection, resolved infection, vaccination immunity, or susceptibility

• Isolated Anti-HBc Positive:

  • Previous resolved infection (low-level anti-HBs undetectable)

  • Occult HBV infection (HBV DNA positive, HBsAg negative)

  • False-positive result

  • Resolving acute infection

Who to Test

• Pregnant women (routine antenatal HBsAg screening)

• Household/sexual contacts of infected individuals

• People at risk (e.g. migrants from intermediate/high-prevalence countries)

• All patients with elevated liver enzymes of unknown cause

• Co-infection screening (Hep B, Hep C, Hep D, and HIV) recommended in higher-risk or uncertain contexts

Follow-Up & Notification

• Acute Hepatitis B: Must be notified to public health authorities

• Chronic Hepatitis B: Notification depends on jurisdiction; typically mandatory in Australia

Notes

• HBsAg: Key marker of infection; if positive for >6 months, indicates chronic infection.

• HBsAb: Confers immunity (either post-infection or post-vaccination).

• HBcAb IgM: Indicates recent/acute infection.

• HBcAb IgG: Signifies past or chronic infection.

• HBV DNA: Determines viral replication level, used for therapy decisions in chronic HBV.

• Vaccination: Check HBsAb post-completion of vaccine series to confirm response if indicated.