|
The influenza vaccine, also known as flu shot, is an annual vaccination using a vaccine that is specific for a given year to protect against the highly variable influenza virus. Each seasonal influenza vaccine contains antigens representing three (trivalent vaccine) or four (quadrivalent vaccine) influenza virus strains: one influenza type A subtype H1N1 virus strain, one influenza type A subtype H3N2 virus strain, and either one or two influenza type B virus strains.〔("Key Facts About Seasonal Flu Vaccine" )〕 Influenza vaccines may be administered as an injection or as a nasal spray. The U.S. Centers for Disease Control and Prevention recommend that everyone over the ages of 6 months should receive the seasonal influenza vaccine. Vaccination campaigns usually focus on people who are at high risk of serious complications if they catch the flu, such as the elderly and people living with chronic illness or those with weakened immune systems, as well as health care workers.〔〔(World Health Organization. Seasonal Influenza )〕 Most flu vaccines provide modest protection against contracting influenza, with the effect seasonably variable depending on antigenic drift. Evidence for protection in adults aged 65 years or older is lacking. A 2014 Cochrane review found a benefit in missed days of work (half a day on average) in the general population. ==Medical uses== According to the Centers for Disease Control and Prevention, the flu vaccine is the best way to protect people against the flu and prevent its spread. The flu vaccine can also reduce the severity of the flu if a person contracts a strain of the flu that the vaccine did not contain.〔(【引用サイトリンク】title=Key Facts About Seasonal Flu Vaccine )〕 It takes about two weeks following vaccination for antibodies to protect against the flu.〔 Influenza vaccine has been demonstrated to reduce disease, hospitalization, and death. The CDC reports that studies demonstrate that vaccination is a cost-effective countermeasure to seasonal outbreaks of influenza.〔(Comparisons of LAIV and TAIV Efficacy ) Centers for Disease Control and Prevention (CDC)〕 A 2012 meta-analysis found that flu shots were efficacious 67 percent of the time; the populations that benefited the most were HIV-positive adults ages 18 to 55 (76 percent), healthy adults ages 18 to 46 (approximately 70 percent), and healthy children ages 6 to 24 months (66 percent). 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「Influenza vaccine」の詳細全文を読む スポンサード リンク
|