Preventing hepatitis A infections in travelers to endemic areas.

In 1995, 24 million travelers from the United States are anticipated to visit developing countries where hepatitis A is endemic. Passive immunization with immune globulin, before exposure or within two weeks following exposure to the hepatitis A virus, protects against clinical disease in < 70-90% of immunized individuals. The duration of protection, measured in months, is relatively short. Active immunization with a single dose of inactivated hepatitis A virus vaccine appears to provide greater protective efficacy and, based on the persistence of vaccine-induced protective antibodies, should provide protection for years. Booster doses given between six and 12 months are likely to provide immunity that may persist for at least a decade. The inactivated hepatitis A vaccine approved for use in the United States has been clinically well-tolerated; mild transient soreness at the injection site is the most frequently reported adverse reaction. Immunization with inactivated hepatitis A vaccine is a safe and effective method for travelers to endemic areas to protect themselves against this infection.