Intro
Hepatitis B is a viral infection that can cause chronic liver disease, cirrhosis and liver cancer. Infants infected early in life have the highest risk of chronic infection.
To prevent this, many countries recommend a hepatitis B vaccine dose at birth, with further doses given during infancy. Others reserve the birth dose for high-risk infants and begin routine doses later.
For a broader overview of hepatitis B, see:
👉 /guides/hepatitis-b
Key Points
- Early-life hepatitis B infection carries a high risk of chronic disease.
- A birth dose provides early protection and acts as a safety net.
- WHO recommends universal birth dose; some countries use selective dosing.
- All infants should complete a full hepatitis B series.
- Australia continues to recommend a universal birth dose.
Background
Hepatitis B virus (HBV) infects the liver. Infants exposed during birth or early childhood have a high chance of developing chronic infection, which can lead to cirrhosis and liver cancer decades later.
Causes or Mechanisms
- Infants are immunologically immature and often fail to clear the virus.
- The vaccine contains HBsAg, which triggers protective antibodies without causing disease.
- A birth dose extends protection into the earliest, highest-risk period of life.
Diagnosis / Treatment / Options
High-risk infants
- Vaccine within 24 hours
- HBIG within 12 hours
- A full 3–4 dose series
Lower-risk infants
Depending on the country:
- Universal birth dose (common in Australia, US historically, many parts of Asia), or
- Delayed first dose at 6–8 weeks for low-risk infants (common in some European systems)
US policy shift
For a full breakdown of the recent US controversy:
👉 /posts/cdc-hepb-birthdose-debate
Completing the series
Regardless of birth dose timing, all infants should complete the series at 2, 4, and 6 months (or equivalent combination schedule).
Risks / Benefits / Prognosis
Benefits
- Early protection against a high-risk infection
- Prevents mother-to-child and early household transmission
- Provides a margin of safety when maternal testing is incomplete
Risks
- Mild redness or fever
- Serious adverse reactions are extremely rare
Prognosis without vaccination
- High likelihood of lifelong infection
- Risk of cirrhosis and liver cancer later in life
FAQ
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Additional Parent Guidance
Questions parents can ask about the hepatitis B birth dose
- “Is my baby at higher risk for hepatitis B?”
- “What are the benefits of giving the vaccine in the first 24 hours?”
- “What are the risks or side effects of the vaccine in newborns?”
- “What happens if we delay the first dose until 6–8 weeks?”
- “How do we make sure my baby completes the full vaccine series?”
- “If this were your baby, what would you do?”
These questions support informed decision-making — not pressure toward any specific choice.