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Two polio vaccines, vaccines against poliomyelitis (polio), are used throughout the world to provide immunity to poliovirus. One uses inactivated (dead) poliovirus and the other uses attenuated (weakened) poliovirus. The vaccines became available in 1955 and 1962, respectively. Interruption of person-to-person transmission of the virus by vaccination has been crucial in global polio eradication, since there is no long term carrier state for poliovirus in immunocompetent individuals, polioviruses have no non-primate reservoir in nature, and survival of the virus in the environment for an extended period of time appears to be remote. The two vaccines have eliminated polio from most countries in the world, and reduced the worldwide incidence from an estimated 350,000 cases in 1988 to just 223 cases in 2012.〔(【引用サイトリンク】Our Progress Against Polio )〕 The first polio vaccine was developed by Jonas Salk in the 1950s. It consists of an injected dose of inactivated (dead) poliovirus. Salk developed it through the use of HeLa cells and first tested it in 1952. It was announced to the world by Dr Thomas Francis Jr. on 12 April 1955.〔(【引用サイトリンク】 publisher=School of Public Health, University of Michigan )〕 A second polio vaccine, this one oral, was developed by Albert Sabin using attenuated (weakened) poliovirus. Human trials of Sabin's vaccine began in 1957, and it was licensed in 1962. In November 2013, the World Health Organization announced a polio outbreak in Syria. In response, the Armenian government put out a notice asking Syrian Armenians under age 15 to get the polio vaccine.〔Lisa Barron, ("Armenian Health Ministry: Syrian Armenian children need polio vaccine" ), ''CISTran Finance'', 4 Nov 2013. Retrieved 18 Dec 2013.〕 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. ==Inactivated vaccine== The Salk vaccine, or ''inactivated poliovirus vaccine'' (IPV), is based on three wild, virulent reference strains, Mahoney (type 1 poliovirus), MEF-1 (type 2 poliovirus), and Saukett (type 3 poliovirus), grown in a type of monkey kidney tissue culture (Vero cell line), which are then inactivated with formalin.〔 The injected Salk vaccine confers IgG-mediated immunity in the bloodstream, which prevents polio infection from progressing to viremia and protects the motor neurons, thus eliminating the risk of bulbar polio and post-polio syndrome. In the United States, vaccine also contains combined diphtheria, tetanus, and acellular pertussis vaccines (DTaP) and a pediatric dose of hepatitis B vaccine.〔 In the UK, IPV is combined with tetanus, diphtheria, pertussis, and ''Haemophilus influenzae'' type b vaccines. When the current formulation of IPV is used, 90% or more of individuals develop protective antibody to all three serotypes of poliovirus after two doses of inactivated polio vaccine (IPV), and at least 99% are immune to poliovirus following three doses. The duration of immunity induced by IPV is not known with certainty, although a complete series is thought to provide protection for many years. 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「Polio vaccine」の詳細全文を読む スポンサード リンク
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