Follow-up immunogenicity of an inactivated hepatitis A virus vaccine in healthy children: results after 5 years

• Published in: Vaccine Vol. 16; no. 2; pp. 232 - 235
• Main Authors: Fan, Pi-Chuan, Chang, Mei-Hwei, Lee, Ping-Ing, Safary, A., Lee, Chin-Yun
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.01.1998; Elsevier
• Subjects: Biological and medical sciences; Child; Child, Preschool; children; Epidemiology. Vaccinations; Female; General aspects; Hepatitis A Vaccines; hepatitis A virus vaccine; Hepatitis A Virus, Human - immunology; Humans; Immunization Programs; Infant; Infectious diseases; long-term immunogenicity; Male; Medical sciences; Sex Factors; Taiwan; Time Factors; Vaccines, Inactivated - immunology; Viral Hepatitis Vaccines - immunology; Taiwan; long-term immunogenicity; children; hepatitis A virus vaccine; Human; Hepatitis A virus; Picornaviridae; Antibody; Vaccination; Hepatic disease; Vaccine; Long term; Hepatovirus; Infection; Virus; Viral hepatitis A; Immunogenicity; Follow up study; Viral disease; Digestive diseases; Child; Humoral immunity; Inactivated strain
• ISSN: 0264-410X; 1873-2518
• DOI: 10.1016/S0264-410X(97)00179-5

Long-term persistence of hepatitis A virus (HAV) serum antibody in vaccinated children has not been demonstrated in previous studies. To study the long-term immunogenicity to HAV vaccine, three doses of strain HM 175 HAV vaccine with 360 enzyme-linked immunosorbent assay units were administered to 107 children, aged from 1.0 to 6.8 years, at 0, 1, and 6 months. The administration of one vaccine dose induced seropositivity (anti-HAV titer ≥20 mIU ml −1) in 95% of all vaccinees at month 1. All subjects remained seropositive until month 6. The titers of HAV antibody remained above 20 mIU ml −1 in all subjects followed up to 60 months. The geometric mean titer (GMT) reached its peak (3802 mIU ml −1) at month 7, i.e. 1 month after the booster dose, and then declined until the end of follow-up at month 60 (661 mIU ml −1). A trend of higher GMT in female subjects persisted up to month 60. The changes of the GMT over time were best described by the regression equation: log (GMT) = 3.26−0.08 × (age in years) ( r = −0.95, P = 0.014). According to this equation, the geometric mean concentration would reach 20 mIU ml −1 at around 24.5 years after the beginning of vaccination. In conclusion, those who completed the recommended three-dose inactivated HAV vaccination series remained seroprotective for at least 5 years. Theoretically, such a vaccination program can provide a protective period of over 20 years in children. This paper may be the first to describe at least 5-year immunogenicity of inactivated HAV vaccination in healthy children.