IMMUNOGENICITY OF INACTIVATED HEPATITIS-A VACCINE IN CHILDREN

Background: Inactivated hepatitis A vaccine is now becoming available in many countries. Methods: To evaluate the immunogenicity and safety of inactivated hepatitis A vaccine in healthy children, 99 susceptible schoolchildren from 4 to 15 years of age received 360 enzyme-linked immunosorbent assay units of the inactivated hepatitis A vaccine at months 0, 1, and 6. Results: Antibody to hepatitis A virus seroconversion (≥20 mlU/mL) was 97% (96/99) in vaccinees after the first dose and 100% after the second (99/99) and booster (96/96) doses. The geometric mean titers of antibody to hepatitis A virus were 167, 465, and 4133 mlU/mL after each dose of vaccine, respectively. There were no significant side effects during the vaccination. Levels of antibody to hepatitis A virus were also tested in 9 susceptible children at day 7 and months 1 and 4 after the intramuscular injection of 2 mL of immune serum globulin. All children had measurable titers of antibody to hepatitis A virus 1 week after receiving immune serum globulin by sensitive enzyme immunoassay, but measurable titers had disappeared 1-4 months later. Conclusions: The inactivated hepatitis A vaccine is safe and immunogenic in healthy children. © 1993.