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Hepatitis A vaccine is a vaccine against the hepatitis A virus. The first successful vaccine against it was invented by Maurice Hilleman at Merck. The vaccine protects against the virus in more than 95% of cases and provides protection from the virus for at least fifteen years.〔 There are two types of vaccines: one type contains inactivated hepatitis A virus, the other contains a live but attenuated virus. Both types stimulate active immunity against a future infection. It is on the World Health Organization's List of Essential Medicines, a list of the most important medication needed in a basic health system. ==Medical uses== Within the US, the vaccine was first phased in around 1996 for children living in high-risk areas. In 1999, it was spread to areas with elevating levels of infection. In the US today, the vaccine is strongly recommended for all children 12 to 23 months of age in an attempt to eradicate the virus nationwide. Although the original FDA license for Havrix by GlaxoSmithKline is dated in 1995, it has been in use in Europe since 1993. According to the US Centers for Disease Control and Prevention, the following people should be vaccinated: all children over one year of age, people whose sexual activity puts them at risk, people with chronic liver disease, people who are being treated with clotting factor concentrates, people working within close proximity to the virus, and people who are living in communities where an outbreak is present. Hepatitis A is the most common vaccine-preventable virus acquired during travel,〔(【引用サイトリンク】 work = Travelers' Health: Yellow Book (CDC) )〕 so people travelling to places where the virus is common like the Indian subcontinent, Africa, Central America, South America, the far East, and Eastern Europe should be vaccinated.〔 The vaccine should be given in the muscle of the upper arm and be given in two doses for the best protection. The initial dose of the vaccine should be followed up by a booster six to twelve months later.〔 Protection against hepatitis A begins approximately two to four weeks after the initial vaccination.〔〔 Protection is proven to last at least 15 years and is estimated to last at least 25 years if the full course is administered. A Cochrane review found that both types of vaccines offer significant protection, for at least two years with the inactivated vaccine and at least five years with the attenuated vaccine. The review also found evidence to conclude that the inactivated vaccine was safe, but required more high quality evidence to assess the safety of the attenuated vaccine. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Hepatitis A vaccine」の詳細全文を読む スポンサード リンク
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