Clinical scenario: mother with hepatitis B | baby vaccination of hep B
A term male infant is born to a 27-year-old mother who was diagnosed during pregnancy with chronic hepatitis B infection. Maternal investigations show HBsAg positive, HBeAg positive, and an HBV DNA level of 8 × 10⁷ IU/mL. The infant weighs 3.2 kg, is clinically well, and is examined within 30 minutes of birth.
What is the most appropriate immediate management to minimize the risk of vertical transmission?
A. Administer hepatitis B vaccine within 24 hours of birth only
B. Administer hepatitis B immune globulin (HBIG) only at birth
C. Administer both hepatitis B vaccine and HBIG at separate injection sites within 12 hours of birth
D. Delay hepatitis B vaccination until maternal HBV DNA results are repeated
E. Start oral entecavir in the newborn
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Correct answer: C. Administer both hepatitis B vaccine and HBIG at separate injection sites within 12 hours of birth
Explanation
Infants born to HBsAg-positive mothers should receive:
- Monovalent hepatitis B vaccine
- Hepatitis B immune globulin (HBIG)
Both should be administered as soon as possible and preferably within 12 hours of birth, using different injection sites.
This combined passive-active immunization reduces the risk of mother-to-child transmission by more than 90–95% when followed by completion of the hepatitis B vaccine series.
Because the mother is HBeAg-positive with a high viral load, she should also have received tenofovir during the third trimester, but this does not alter the newborn’s management.
Why the other options are incorrect
A. Hepatitis B vaccine only
- Insufficient for infants born to HBsAg-positive mothers when HBIG is available.
B. HBIG only
- Passive immunity alone is inadequate without active immunization.
D. Delay vaccination
- Vaccination should never be delayed while awaiting additional maternal investigations.
E. Oral entecavir
- Antiviral therapy is not indicated in newborns for post-exposure prophylaxis.
High-yield pearl
After completing the hepatitis B vaccine series, infants born to HBsAg-positive mothers should undergo post-vaccination serologic testing (HBsAg and anti-HBs) at 9–12 months of age, or 1–2 months after the final vaccine dose if the series is delayed, to confirm protection and exclude infection.
