title: Follow-up immunogenicity of an inactivated hepatitis A virus vaccine in healthy children: results after 5 years.
abstract: 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 > or = 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 x (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.
authors.affiliation: Department of Pediatrics, College of Medicine, National Taiwan University, Taipei, Taiwan.
authors.forename: P C
authors.initials: PC
authors.lastname: Fan
authors.forename: M H
authors.initials: MH
authors.lastname: Chang
authors.forename: P I
authors.initials: PI
authors.lastname: Lee
authors.forename: A
authors.initials: A
authors.lastname: Safary
authors.forename: C Y
authors.initials: CY
authors.lastname: Lee
mesh_terms: D002648:Child; D002675:Child, Preschool; D005260:Female; D022362:Hepatitis A Vaccines; D017957:Hepatitis A Virus, Human / Q000276:immunology*; D006801:Humans; D017589:Immunization Programs; D007223:Infant; D008297:Male; D012737:Sex Factors; D013624:Taiwan; D013997:Time Factors; D015164:Vaccines, Inactivated / Q000276:immunology; D014761:Viral Hepatitis Vaccines / Q000276:immunology*
chemical_list: D022362:Hepatitis A Vaccines; D015164:Vaccines, Inactivated; D014761:Viral Hepatitis Vaccines