Safety and Serological Effect of Revaccination of Inactivated Hepatitis A Vaccine and Combined Inactivated Hepatitis A and B Vaccine in Healthy Children

ObjectiveTo evaluate the secondary immunization serological effects and safety of inactivated hepatitis A vaccine(HepA-I)and combined inactivated hepatitis A and B vaccine(HepAB-I). MethodsAn open, controlled clinical trial was conducted in 210 healthy children aged 24-38 months old who completed full immunization schedule of hepatitis B vaccine and had been vaccinated with hepatitis A attenuated live vaccine(HepA-L)over 6 months old. All the children were randomly divided into 2 groups; one group vaccinated with one dose HepA-I, the other vaccinated with one dose combined HepAB-I. Antibodies to hepatitis A virus(Anti-HAV)titers and antibody to Hepatitis B Virus Surface Antigen(Anti-HBs)titers were tested before and one month after vaccination. Potential adverse reactions were observed within 72 hours after vaccination.ResultsHepA-I group Anti-HAV Positive(≥20mIU/ ml)rate increase from 95.1%to 100.0%and the geometric mean concentration(GMC)increase from 124.41mIU/ml to7269.31mIU/ml(increased by 55.74times). HepAB-I group Anti-HAV rate increase from 88.8%to 98.9%and the Anti-HAV GMC increase from 98.03mIU/ml to 5174.76mIU/ml(increased by 58.35 times). The Anti-HBs positive(≥10mIU/ml)rate increase from 72.9%to 97.8%and the Anti-HBs GMC increase from 22.20mIU/ml to 1226.14mIU/ml(increased by 54.49 times)12 cases with adverse reactions were observed and all of them were fever. The incidence was 5.7%and no other adverse reactions. ConclusionSecondary immunization of(HepA-I)and(HepAB-I)showed effective serological effects and good safety in children.