Why is it important to vaccinate newborns against Hepatitis B (HB)?

Importance of Hepatitis B Vaccination for Newborns

Vaccinating newborns against Hepatitis B is critically important because infants who become infected have up to a 90% risk of developing chronic infection, with 25% eventually dying from chronic liver disease as adults. 1

High Risk of Chronic Infection in Infants

The risk of developing chronic HBV infection after exposure varies dramatically by age:

• Infants infected perinatally: 70-90% become chronically infected 2
• Children infected before age 5: 20-50% become chronically infected 2
• Older children and adults: Only 5-10% become chronically infected 2

This inverse relationship between age and chronicity risk makes newborn vaccination particularly crucial. While only about 8% of acute infections occur in children under 10 years, these infections account for 20-30% of all chronic infections in the United States 2.

Severe Long-Term Consequences

Chronic HBV infection leads to:

• Chronic active hepatitis
• Cirrhosis of the liver
• Primary hepatocellular carcinoma (liver cancer)

The hepatitis B vaccine is recognized as the first anti-cancer vaccine because it prevents primary liver cancer 3. Studies in Taiwan and Korea have demonstrated decreased incidence of hepatocellular carcinoma following implementation of universal childhood immunization against HBV 3.

Transmission Routes to Newborns

Infants can acquire HBV infection through:

1. Perinatal transmission: From HBsAg-positive mothers during birth
2. Horizontal transmission: From infected household contacts during early childhood

Without intervention, infants born to HBsAg and HBeAg positive mothers have a 70-90% risk of infection 1.

Effectiveness of Vaccination

• When combined with Hepatitis B Immune Globulin (HBIG), vaccination provides >90% protection against perinatal HBV transmission 4
• Even without HBIG, higher-dose vaccination starting at birth can provide high protective efficacy if the second dose follows within 2 months 5

Universal Vaccination Strategy

The Advisory Committee on Immunization Practices (ACIP) recommends universal infant vaccination because:

1. Targeted risk-based strategies failed: Selective vaccination of high-risk groups has not lowered the overall incidence of hepatitis B infection 1
2. Difficulty identifying all at-risk infants: Many infected persons have no identifiable source for their infections 1
3. High coverage potential: Vaccination can be integrated into existing childhood immunization schedules 1

Implementation Recommendations

• All infants should receive their first dose of hepatitis B vaccine within 12 hours of birth 1
• For infants born to HBsAg-positive mothers, both HBIG and hepatitis B vaccine should be administered within 12 hours of birth 1
• The vaccine series should be completed according to recommended schedules, with the final dose not administered before 24 weeks of age 1

Special Considerations

• Preterm infants: For those weighing <2,000g, the birth dose should not be counted as part of the vaccine series due to potentially reduced immunogenicity; they should receive a total of 4 doses 1
• Breastfeeding: Infants born to HBsAg-positive mothers who receive prophylaxis may be breastfed immediately after birth 1

Global Impact

Universal newborn HBV vaccination programs have been implemented in 168 countries as of 2006 6. These programs have shown significant impact on reducing the global burden of HBV infection and are considered the preferred strategy for controlling hepatitis B worldwide 6.

By preventing chronic infection in infancy, hepatitis B vaccination significantly reduces morbidity, mortality, and improves quality of life for millions of people globally.