According to IAP immunisation guidelines, what is the preferred vaccine for primary immunisation against hepatitis B in a newborn born to a hepatitis B surface antigen (HBsAg) positive mother?

Explanation

## Hepatitis B Immunisation in Infants Born to HBsAg-Positive Mothers **Key Point:** Infants born to HBsAg-positive mothers require BOTH hepatitis B vaccine AND hepatitis B immunoglobulin (HBIG) within 12–24 hours of birth to prevent vertical transmission and ensure seroconversion. ### Rationale for Combined Approach The combination strategy provides: - **Passive immunity** from HBIG (anti-HBs antibodies) — immediate protection against maternal HBV - **Active immunity** from the vaccine — long-term protective response This dual approach reduces the risk of chronic HBV infection from ~90% (if untreated) to <5% when both agents are given promptly. ### IAP Immunisation Schedule for HBsAg-Positive Mothers | Timing | Intervention | Route | | --- | --- | --- | | Within 12–24 hours of birth | Hepatitis B vaccine (monovalent) + HBIG | IM (separate sites) | | 6 weeks | Hepatitis B vaccine (2nd dose) | IM | | 10 weeks | Hepatitis B vaccine (3rd dose) | IM | | 14 weeks | Hepatitis B vaccine (4th dose) | IM | | 9–12 months | Anti-HBs testing | Serology | **High-Yield:** The monovalent vaccine is preferred at birth (not pentavalent) because it allows precise dosing and timing without unnecessary additional antigens in the immediate neonatal period. **Clinical Pearl:** HBIG must be given at a different anatomical site from the vaccine to avoid neutralisation of the vaccine virus by passive antibodies. ### Why Monovalent at Birth? - Pentavalent vaccine (DPT + HBV + IPV) is introduced at 6 weeks, not at birth - Birth dose of HBV monovalent ensures rapid passive + active protection before the infant's immune system encounters maternal HBsAg - Subsequent doses follow the standard IAP schedule [cite:IAP Immunisation Guidelines 2023]