Hepatitis A is a self-limiting inflammation of the liver, which is caused by the hepatitis A virus. The infection is rare in industrialized countries but highly endemic in many developing countries. Until recently, only short-lived protection was possible using human immunoglobulin, but inactivated hepatitis A vaccines have now become available. An alum-adsorbed vaccine (Havrix®, SmithKline Beecham Biologicals, Rixensart, Belgium) has been licensed in several countries and a similar preparation (Merck Sharp & Dohme, West Point, Pennsylvania, USA) is being reviewed by licensing authorities. An alum-free vaccine using a liposomal adjuvant principle (Epaxal®, Swiss Serum and Vaccine Institute, Berne, Switzerland) is available in Switzerland. All three vaccines are highly immunogenic. Local adverse effects occur less frequently with the alum-free, liposomal vaccine. Protective efficacy has been shown to be near 100% for both alum-based vaccines. Efficacy trials for the liposomal vaccine have not been reported. Travellers to endemic regions, in particular backpackers and those intending to stay for long periods, should be vaccinated 1 month before departure. One or two booster injections are warranted during the first year after initial vaccination. For other groups of persons potentially at risk, the specific epidemiological situation should be evaluated before deciding for or against vaccination. This includes intravenous drug users, children and staff at day-care centers and hospitals, homosexual men, food handlers and sewage workers. Although the incidence of hepatitis A in the population at large will probably change little with the advent of the inactivated vaccines, they can improve protection of those individuals and groups known to be at high risk of infection.
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