What Does a Positive Anti-HBc Show?
A positive anti-HBc (total antibody to hepatitis B core antigen) indicates past or present hepatitis B virus infection and persists for life in the majority of persons. 1
Anti-HBc Cannot Stand Alone
Anti-HBc positivity by itself does not distinguish between acute, chronic, or resolved infection—you must obtain additional serologic markers (HBsAg, anti-HBs, and IgM anti-HBc) to determine the infection state. 2
Interpretation Based on Complete Serologic Panel
The meaning of positive anti-HBc depends entirely on the accompanying markers:
Active Infection Patterns
- HBsAg positive + Total anti-HBc positive + IgM anti-HBc positive = Acute hepatitis B infection 2
- HBsAg positive + Total anti-HBc positive + IgM anti-HBc negative = Chronic hepatitis B infection 2
Resolved Infection Pattern
- HBsAg negative + Total anti-HBc positive + Anti-HBs positive = Past infection with immunity 2
Vaccination Pattern (for comparison)
- HBsAg negative + Anti-HBs positive + Anti-HBc negative = Immunity from vaccination (not natural infection) 2
Isolated Anti-HBc Positivity (No Other Markers Present)
When anti-HBc is the only detectable marker, this represents one of three scenarios: 1
Resolved infection with waning anti-HBs (most common in high-prevalence populations)—the person recovered but protective antibody levels have declined over time 1
Occult chronic infection—HBsAg is present but below the detection threshold of commercial assays; HBV DNA can be isolated from blood in less than 5% of these cases 1
False-positive reaction 1
In low-prevalence populations, isolated anti-HBc occurs in 10-20% of persons with serologic markers of HBV infection, and most will demonstrate a primary response after hepatitis B vaccination. 1
Critical Clinical Considerations
Infectivity Risk
Persons positive only for anti-HBc are unlikely to be infectious except under unusual circumstances involving direct percutaneous exposure to substantial quantities of virus (e.g., blood transfusion or organ transplant). 1, 2
Reactivation Risk
Patients who are anti-HBc positive face risk of HBV reactivation with profound immunosuppression. 2 Measure serum HBV DNA before starting immunosuppressive therapy to define reactivation risk. 2
IgM Anti-HBc Testing Pitfall
IgM anti-HBc testing should be limited to persons with clinical evidence of acute hepatitis or epidemiologic link to HBV infection due to low positive predictive value in asymptomatic persons. 2 Do not order this test routinely in asymptomatic individuals. 1
Timeline of Anti-HBc Appearance
Anti-HBc appears at the onset of symptoms or liver-test abnormalities in acute HBV infection. 1 The IgM class of anti-HBc is detected at the onset of acute hepatitis B and persists for up to 6 months if the infection resolves. 1 After resolution, total anti-HBc (predominantly IgG) persists indefinitely. 1
Next Steps When Anti-HBc is Positive
If you encounter a positive anti-HBc result, immediately order: 2
- HBsAg to determine if active infection is present
- Anti-HBs to determine if protective immunity exists
- IgM anti-HBc (only if clinical hepatitis or known exposure) to distinguish acute from chronic infection
If HBsAg is positive, proceed with HBV DNA quantification, ALT measurement, and HBeAg/anti-HBe testing to determine disease phase and treatment need. 3