The value of immunization against hepatitis A.

Safe and effective inactivated vaccines should soon be available for prevention of hepatitis A virus infections in the United States. Here we review the heterogeneous distribution of hepatitis A cases among different risk groups, age groups, and geographic regions of the United States and comment on several possible strategies for using hepatitis A vaccines in immunization programs. We conclude that immunization targeted exclusively at groups that are at high risk of developing hepatitis A is unlikely to significantly lower national rates of the disease. While universal immunization of young children may accomplish this goal, such a practice is likely to prove unacceptably costly. Alternative strategies worthy of consideration include immunization targeted to specific risk groups on a regional basis, based on knowledge of the local epidemiology of hepatitis A.