Persistence of seropositivity among persons vaccinated for hepatitis A during infancy by maternal antibody status: 15‐year follow‐up

The effect of passively transferred maternal antibody to hepatitis A virus (anti‐HAV) on the duration of seropositivity after hepatitis A vaccination during infancy and early childhood is unclear. We obtained levels of anti‐HAV at intervals through age 15‐16 years among three groups of Alaskan Native children who initiated a two‐dose inactivated hepatitis A vaccination series at ages 6 months (group 1), 12 months (group 2), and 15 months (group 3), each group randomized according to maternal anti‐HAV status. Seropositivity (anti‐HAV ≥20 mIU/mL) 30 years after the second vaccine dose among the three groups was predicted using a random effects model. One hundred eighty‐three children participated in the study; follow‐up did not differ significantly by vaccine group or maternal anti‐HAV status. Although the frequency of seropositivity among all participants through age 10 years was high (100% among groups 2 and 3 and >90% among group 1), there was a decrease thereafter through age 15‐16 years among group 1 children, who initiated vaccination at age 6 months (50%‐75%), and among maternal anti‐HAV‐positive children in groups 2 and 3 (67%‐87%), who initiated vaccination at ages 12 months and 15 months, respectively. Nonetheless, the model indicated that anti‐HAV seropositivity should persist for ≥30 years after vaccination in 64% of all participants; among those seropositive at age 15‐16 years, 84% were predicted to remain so for ≥30 years. Conclusion : Most children vaccinated during early childhood available for sampling maintained seropositivity through age 15‐16 years; however, seropositivity was less frequent among those starting vaccination at age 6 months and among maternal antibody‐positive participants who started vaccination at age 12 months or 15 months; overall, our findings support current vaccine recommendations and continued follow‐up of this cohort. (H epatology 2016;63:703–711)