Inactivated hepatitis A vaccine in childhood: implications for disease control

Abstract The experience to date with the Merck inactivated hepatitis A vaccine in healthy children 2–16 years old is reviewed. Comparison of responses to increasing doses indicates that an intramuscular dose of 25 units results in seroconversion of 99% of children by week 4 following a single dose. Antibody persistence rate is nearly 100% six months later, whether or not a second priming dose is given at week 8. This vaccine has proven highly immunogenic in children and has a favourable safety/tolerability profile. It should be useful for pre-exposure prophylaxis and control of hepatitis A, and should eventually replace immune globulin (Ig) for this indication.