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MI4.7-9 | Viral Hepatitis — SDL Guide (Part 3)

Prevention: Hepatitis B Vaccination

The hepatitis B vaccine is a recombinant subunit vaccine containing only HBsAg expressed in yeast (Saccharomyces cerevisiae). It is the only vaccine against a human cancer (hepatocellular carcinoma).

Schedule in India (National Immunization Schedule):
- Birth dose (within 24 hours) — crucial to prevent vertical transmission
- 6 weeks, 10 weeks, 14 weeks — as pentavalent vaccine (DTP-HepB-Hib)

Post-vaccination serology: Only anti-HBs is generated (no anti-HBc — no natural infection). Protective level: anti-HBs ≥10 mIU/mL.

Post-exposure prophylaxis (HBIG + vaccine):
- Needlestick from HBsAg-positive source: Hepatitis B Immunoglobulin (HBIG) within 24 hours + start/complete vaccine series
- Neonate of HBsAg-positive mother: HBIG + birth dose vaccine within 12 hours

Infographic comparing HBV vaccination, recovered natural infection, acute infection, and the window period using key serologic markers. — **Panel A:** HBV serology timeline showing HBsAg, anti-HBc IgM, anti-HBc IgG, anti-HBs, and highlighted window period. **Panel B:** Vaccinated pattern showing anti-HBs alone positive with HBsAg, anti-HBc IgM, and anti-HBc IgG negative. **Panel C:** Recovered natural infection pattern showing anti-HBs and anti-HBc IgG positive with HBsAg and anti-HBc IgM negative. **Panel D:** Acute HBV infection pattern showing HBsAg and anti-HBc IgM positive with anti-HBs negative. **Panel E:** Clinical pearl callout showing window-period trap, negative HBsAg limitation, anti-HBc IgM testing, and blood bank anti-HBc screening.

CLINICAL PEARL

The window period trap: In early acute HBV, HBsAg may become undetectable (cleared) before anti-HBs appears — the 'window period.' During this time, the ONLY marker present is anti-HBc IgM. Blood banks screen for anti-HBc to catch window-period donors. In a patient with acute hepatitis, negative HBsAg does NOT exclude HBV — always send anti-HBc IgM when clinical suspicion is high.