A newborn's mother is discovered to be HBsAg positive. Which of the following would you recommend for this infant?

• A. Give BOTH the Hep B vaccine and immunoglobulin
• B. Hep B vaccine only
• C. HBIG only
• D. No treatment

Answer: (A)

When a newborn’s mother is hepatitis B surface antigen (HBsAg) positive, the baby is at high risk for perinatal infection. The best approach is to give both components right after birth: the hepatitis B vaccine and hepatitis B immune globulin (HBIG), ideally within 12 hours. The vaccine starts the child’s long-term protection by stimulating active immunity, while HBIG provides immediate passive antibodies to block infection during the early period before the vaccine can take effect. This dual prophylaxis substantially lowers the risk of the infant developing chronic hepatitis B. After this, the infant should complete the standard hepatitis B vaccination series. The reason this is preferred over vaccine alone or HBIG alone is that the vaccine alone misses the immediate window of exposure, and HBIG alone won’t establish long-lasting immunity. No treatment would leave the infant at high risk for infection.