Assessment of immune responses to hepatitis A vaccination in children aged 1 and 2 years

Abstract

Aim: Hepatitis A can be prevented by vaccination. The aim of this study was to determine seropositivity for hepatitis A before vaccination in healthy children 12 and 24 months of age and compare seroconversion rates after vaccination between these 2 groups.

Materials and methods: Forty-nine children aged 1 year (Group 1) and 51 children aged 2 years (Group 2) were included in the study. Inactive hepatitis A vaccine (Avaxim, 80 antigenic subtypes, 0.5 mL) were administered to every child in 2 doses, 6 months apart. Anti-hepatitis A virus (HAV) IgG and IgM antibodies were detected by Architect HAVAb-IgG and HAVAb-IgM (Abbott, Wiesbaden, Germany) test kits.

Results: Nine percent of the children were seropositive for anti-HAV IgG before vaccination. The seroconversion rate at 2 weeks was 34% and 44% in Group 1 and Group 2, respectively. At 4 weeks the seroconversion rate was 87.7% and 90.1% in Group 1 and Group 2, respectively. All of the children who completed the vaccination program were seropositive at 28 weeks (after the second dose). No serious adverse reaction was observed in any of the children.

Conclusion: It was determined that Avaxim, including 80 antigen units, is safe and immunogenic in healthy children 12 and 24 months of age.