title: Hepatitis A vaccine: immunogenicity following administration of a delayed immunization schedule in infants, children and adults.
abstract: Current immunization schedules for hepatitis A vaccine specify administration of a booster within 6-12 or 6-18 months of the primary dose. However, there may be circumstances that disrupt this schedule and the efficacy of administering a booster beyond the recommended time is a practical concern for healthcare providers. In this study, a booster was administered to 268 participants (137: <18 years old), an average of 27 months (range 20-31) after the primary dose. In those tested after the booster, the median anti-HAV GMT was 1544 milli-international units per milliliter (mIU/ml). Response to a delayed booster was strong in children over 2 years old (GMT 1500-1960 mIU/ml) and adults (GMT 1622 mIU/ml), but was significantly lower in children under 2 years old (GMT 1109 mIU/ml). Findings suggest a booster administered 20-31 months after the primary dose is immunogenic and GMT in persons >2 years of age were comparable to those seen in adults and children who receive hepatitis A vaccine per schedule.
authors.affiliation: Viral Hepatitis Program, Alaska Native Medical Center, ANC-HEP, 4315 Diplomacy Drive, 99508, Anchorage, AK, USA. jwilliam@anmc.org
authors.forename: James L
authors.initials: JL
authors.lastname: Williams
authors.forename: Dana A
authors.initials: DA
authors.lastname: Bruden
authors.forename: Henry H
authors.initials: HH
authors.lastname: Cagle
authors.forename: Brian J
authors.initials: BJ
authors.lastname: McMahon
authors.forename: Susan E
authors.initials: SE
authors.lastname: Negus
authors.forename: Carol J
authors.initials: CJ
authors.lastname: Christensen
authors.forename: Mary M
authors.initials: MM
authors.lastname: Snowball
authors.forename: Lisa R
authors.initials: LR
authors.lastname: Bulkow
authors.forename: Leslie K
authors.initials: LK
authors.lastname: Fox-Leyva
mesh_terms: D000293:Adolescent; D000328:Adult; D000375:Aging / Q000276:immunology; D000413:Alaska; D002648:Child; D002675:Child, Preschool; D004196:Disease Outbreaks; D004306:Dose-Response Relationship, Immunologic; D005260:Female; D035922:Hepatitis A Antibodies / Q000032:analysis / Q000096:biosynthesis; D022362:Hepatitis A Vaccines / Q000008:administration & dosage / Q000276:immunology*; D006801:Humans; D007115:Immunization Schedule; D007117:Immunization, Secondary; D007223:Infant; D008297:Male
chemical_list: D035922:Hepatitis A Antibodies; D022362:Hepatitis A Vaccines