Preventing Vertical (Mother-to-Child) Transmission of Hepatitis B

Vertical transmission of Hepatitis B virus (HBV) most often occurs during delivery through exposure to maternal blood and fluids. Current guidelines (WHO/CDC/AASLD) recommend a combined strategy for infants born to HBsAg-positive mothers, which includes both active and passive immunisation of the newborn plus maternal antiviral therapy in the third trimester when viral load is high. All three interventions listed are correct, making 1, 2 and 3 the right combination.

Analysis of Each Statement

• 1. Passive immunisation of infant at birth (correct): Hepatitis B immunoglobulin (HBIG) is given to the newborn within 12 hours of birth. It provides immediate, temporary antibody protection, neutralising any virus the infant may have been exposed to during delivery, until the infant's own active immunity develops.
• 2. Active immunisation of infant at birth (correct): The first dose of the Hepatitis B vaccine is administered to every newborn within 24 hours of birth (birth dose), regardless of maternal status, and is the single most effective measure for preventing chronic HBV infection in the infant. Given together with HBIG (at a different injection site) for infants of HBsAg-positive mothers, it achieves >90% efficacy in preventing vertical transmission.
• 3. Antiviral therapy in the third trimester for high viral load mothers (correct): When maternal HBV-DNA exceeds 2,00,000 IU/mL, the risk of transmission persists even with infant immunoprophylaxis. Starting antivirals such as tenofovir in the late second/third trimester (around 28–32 weeks) lowers maternal viraemia and further reduces the residual risk of transmission.

Why the Other Options Are Wrong

• "1 and 2 only": Omits maternal antiviral therapy, which is essential in high-viral-load mothers since immunoprophylaxis alone still carries a meaningful transmission-failure rate in this group.
• "2 and 3 only": Omits passive immunisation (HBIG). Active vaccine alone takes time to generate protective antibody titres, so HBIG is needed to provide immediate cover during this window — combined immunoprophylaxis is the standard of care, not vaccine alone.
• "1 and 3 only": Omits active immunisation (the birth-dose Hepatitis B vaccine). This is incorrect because the vaccine — not just HBIG — is what generates the infant's own durable, long-term immunity; HBIG alone only offers short-lived passive protection and cannot be relied upon in isolation.

Conclusion

All three measures — passive immunisation (HBIG), active immunisation (HepB vaccine) at birth, and third-trimester maternal antiviral therapy for high HBV-DNA levels — act together and are all necessary for optimal prevention of vertical HBV transmission. The correct answer is therefore 1, 2 and 3.