Hepatitis A, B, C and E in children — formative SAQs

SAQ 1 (10 marks)

A term infant is delivered vaginally to a mother known to be hepatitis B surface-antigen positive and hepatitis B e-antigen positive with a high HBV DNA. The midwife asks you what must be done for the baby. ^[4]

Question: Outline the prevention pathway for this neonate, including the rationale, the specific interventions, the timing, and the follow-up testing. (10 marks) ^[6]

Model answer

Rationale and transmission risk (2 marks). A mother who is HBsAg and HBeAg positive with high HBV DNA has the highest vertical-transmission risk; without immunoprophylaxis, the majority of such neonates become chronic carriers because the immature immune system enters an immune-tolerant phase that lets the virus persist. Chronic carriage carries a lifetime risk of cirrhosis and hepatocellular carcinoma, so preventing the infection at birth is the single most impactful intervention in the whole topic. ^{[4] [6]}

The birth-dose bundle — vaccine and immunoglobulin (3 marks). The baby must receive the hepatitis B vaccine AND hepatitis B immunoglobulin (HBIG) within 24 hours of birth, ideally within 12 hours, given at separate intramuscular injection sites. This is the non-negotiable, never-miss bundle: the vaccine induces active immunity while the HBIG provides immediate passive antibody cover during the window before the vaccine response develops. The hepatitis B vaccine series is then completed through infancy on the standard schedule. ^{[4] [6]}

Maternal suppression and the delivery context (2 marks). For a high-viraemic mother, maternal tenofovir in the third trimester further suppresses HBV DNA and reduces the residual transmission that immunoprophylaxis alone does not prevent; in this case the antenatal window has passed, but the principle frames why antenatal HBV DNA testing and maternal suppression are offered. Mode of delivery is not altered for hepatitis B alone, and breastfeeding is not contraindicated once the baby has received immunoprophylaxis. ^{[4] [6]}

Follow-up testing and surveillance (2 marks). At 9 to 12 months of age, test the infant for HBsAg and anti-HBs: a negative HBsAg with positive anti-HBs confirms protection; a positive HBsAg indicates chronic carriage and triggers lifelong surveillance. The infected infant is referred to paediatric hepatology for ALT and HBV DNA monitoring, fibrosis assessment and hepatocellular-carcinoma surveillance, with vaccination of susceptible household contacts. ^[6]

Safety-net and family (1 mark). The family is counselled, household and sexual contacts are screened and vaccinated, and the child's records flag the chronic hepatitis B status for transition to adult care. The lesson is that this bundle, delivered within twenty-four hours, is what prevents a lifetime of chronic liver disease. ^{[4] [6]}