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在疫苗前时代,感染脊髓灰质炎(脊灰)野病毒[Wild Poliovirus(PV),WPV]在全球较为普遍,温带地区在夏季和秋季出现季节性高峰及流行。1955年灭活脊灰病毒疫苗(Inactivated PV Vaccine,IPV)和20世纪60年代口服脊灰减毒活疫苗(Oral Poliomyelitis Attenuated Live Vaccine,OPV)获得上市许可后,脊灰病例数在美国急剧下降。美国最后一例本土WPV病例发生在1979年,最后一例美国公民在国外旅行感染WPV发生在1986年,最后一例WPV输入病例发生在
In the pre-vaccination era, wild poliovirus (WP) infection with poliovirus (PV), WPV] is prevalent in the world, with seasonal peaks and prevalence in temperate regions in summer and autumn. The number of polio cases dropped sharply in the United States following the listing approval of Inactivated PV Vaccine (IVV) in 1955 and Oral Poliomyelitis Attenuated Live Vaccine (OPV) in the 1960s. The last case of native WPV in the United States occurred in 1979 and the last case of a U.S. citizen traveling in a foreign country contracted WPV occurred in 1986, with the last case of WPV occurring