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自脊髓灰质炎(简称脊灰炎下同)疫苗问世以来,世界上不少国家和地区已有效地控制了脊灰炎的发生和流行。但Mclselaar提出:随着卫生生活条件的改善,脊灰炎病毒毒力可选择地提高;Wyatt也提出免疫裂隙(immunization gap)之说,是实行计划免疫国家发生暴发流行的潜在危险。
Since the advent of poliomyelitis (hereinafter referred to as polio) vaccine, many countries and regions in the world have effectively controlled the occurrence and prevalence of polio. However, Mclselaar suggested that the poliovirus virulence may be selectively increased as the sanitary living conditions improve. Wyatt also proposed the immunization gap as a potential danger of an outbreak in a planned immunization country.