Key result
Hepatitis A booster at age 4 linked to 100% seropositivity at one month.
Why the study?
Few data are available regarding hepatitis A vaccine immunogenicity and safety in children younger than 2 years of age after infant immunization.
Does revaccination with hepatitis A vaccine at 4 years of age improve antibody titers in children previously vaccinated in infancy?
Cohort (n=44)
Does revaccination with hepatitis A vaccine at 4 years of age improve antibody titers in children previously vaccinated in infancy?
Absolute Event Rate: 100% vs 77.3%
A hepatitis A booster dose at 4 years of age is highly immunogenic and safe in children who received infant immunization.
Supports immunogenicity of a 4-year booster in infant-vaccinated children; leaves open whether this strategy enhances durable protection.
BACKGROUND: Hepatitis A vaccine provides long term protection against hepatitis A infection in adults and children older than 2 years of age. Few data are available regarding children younger than 2 years of age. METHODS: Children who were vaccinated in infancy with hepatitis A vaccine were revaccinated at 4 years of age, and antibody titers were followed. Forty-four subjects who had been vaccinated with hepatitis A vaccine [Havrix, 360 enzyme-linked immunosorbent assay units (EU)] at the age of 2, 4 and 6 months were revaccinated with 720 EU of inactivated hepatitis A vaccine (Havrix) at 4 years of age. RESULTS: Geometric mean titer (GMT) of 44 evaluable cases was 41 mIU/ml and 34 children (77.3%) were seropositive before the booster dose. Postvaccination blood samples were obtained from 37 cases. One month after booster dose GMT increased to 2884 mIU/ml, and all subjects were seropositive. Ten seronegative cases also seroconverted. The GMT of the seropositive cases showed anamnestic response after the booster dose (57 mIU/ml before booster dose, 5623 mIU/ml after the booster). No serious adverse event was seen after the booster dose. CONCLUSION: We conclude that childhood hepatitis A virus revaccination after infant immunization is highly immunogenic and safe.
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Kanra et al. (2002) conducted a cohort in Hepatitis A immunization (n=44). Hepatitis A booster vaccine (Havrix) vs. Baseline (pre-booster) was evaluated on Seropositivity 1 month after booster dose. A hepatitis A booster vaccine administered at 4 years of age to children immunized in infancy resulted in 100% seropositivity and a geometric mean titer of 2884 mIU/ml at 1 month.
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