由于卫生条件的改善,甲型肝炎在北欧、西欧国家和美国已少见,主要传染源是到高甲肝流行地区(例如热带与亚热带)去旅行的居民。自从有了甲肝灭活疫苗,到这些地区旅行前应用免疫球蛋白被动免疫,已有可能用主动免疫替代,后者所形成的免疫保护期长于前者,初步研究指出,灭活甲肝疫苗具有 Hepatitis A has become rare in northern and western European countries and the United States as a result of improved sanitation. The main source of infection is residents traveling to endemic areas such as the tropics and subtropics. Since the introduction of a hepatitis A inactivated vaccine, passive immunization with immunoglobulin before traveling in these areas has been replaced by active immunization, which results in a longer duration of protection than the former, and preliminary studies indicate that inactivated hepatitis A vaccine has