MicrobiologyTier 2Medical Sciences concept

Hepatitis B serology interpretation (HBsAg, anti-HBc IgM/IgG, HBeAg)

Core concept

HBsAg = current infection present (acute or chronic)
Anti-HBc IgM = acute/recent infection (<6 months)
Anti-HBc IgG = past exposure - with anti-HBs (resolved) or with HBsAg (chronic)
Anti-HBs = immunity - from vaccination or resolved infection
HBeAg = active viral replication, high infectivity

Key detail

HBsAg	Anti-HBc	Anti-HBs	Interpretation
+	IgM+	-	Acute infection
+	IgG+	-	Chronic infection
-	IgG+	+	Resolved infection
-	-	+	Vaccination (isolated anti-HBs)
-	IgG+ only	-	"Window period" or occult infection

"Window period": HBsAg cleared, anti-HBs not yet risen - anti-HBc IgM may be the only positive marker
HBeAg+ or high HBV DNA -> highest risk of vertical (mother-to-child) transmission

Clinical relevance

Vertical transmission risk stratifies maternal antiviral therapy and neonatal prophylaxis timing
HBeAg+ mother or HBV DNA >200,000 IU/mL -> antiviral (tenofovir) from third trimester + neonatal HBIG and vaccine within 12h of birth
Isolated anti-HBc (core antibody alone) -> consider occult HBV, especially before immunosuppressive therapy (reactivation risk)

Correlations

Hepatitis B reactivation with immunosuppression (rituximab, chemotherapy)
Chronic hepatitis B antiviral management
Needlestick/occupational exposure serology algorithms

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