Nathanson N
Rev Infect Dis. 1984 May-Jun;6 Suppl 2:S308-12. doi: 10.1093/clinids/6.supplement_2.s308.
Mass immunization with oral poliovirus vaccine was begun in the United States in 1963, and the last outbreak of natural poliomyelitis occurred in 1972. In the subsequent 10 years, there has been only one outbreak, in 1979, due to the introduction of wild polio-virus to an underimmunized Amish population. Paradoxically, eradication occurred even though 5%-10% of the population zero to 14 years of age were unimmunized and susceptible. It is suggested that this eradication was due to two factors. First, the marked seasonality of poliovirus infections, imposed on a reduced number of susceptibles , led to wintertime fade-outs of wild poliovirus over sizable areas. Second, although reintroductions into virus-free areas did occur, they did not equal the frequency of fade-outs. This led, in turn, to an annual stepwise reduction in the number of infected states over a 10-year period, culminating in eradication. Measles makes an instructive comparison because it has more stubbornly resisted eradication. Although regional fade-outs of measles have occurred regularly during the seasonal low, measles is more frequently reintroduced because of its greater transmissibility. It is suggested that this difference in reintroduction was a critical determinant of the difference between the eradicability of measles and poliomyelitis.
美国于1963年开始大规模口服脊髓灰质炎疫苗免疫接种，最后一次自然脊髓灰质炎疫情发生在1972年。在随后的10年里，仅在1979年发生过一次疫情，原因是野生脊髓灰质炎病毒传入了免疫接种率低的阿米什人群体。矛盾的是，尽管0至14岁人群中有5% - 10%未接种疫苗且易感染，但脊髓灰质炎仍被根除了。有人认为，这种根除归因于两个因素。首先，脊髓灰质炎病毒感染具有明显的季节性，在易感人群数量减少的情况下，导致野生脊髓灰质炎病毒在相当大的区域在冬季消失。其次，尽管确实有病毒传入无病毒地区的情况发生，但传入频率低于消失频率。这反过来又导致在10年期间感染州的数量逐年逐步减少，最终实现根除。麻疹是一个有启发性的对比对象，因为它更顽固地抵制根除。尽管麻疹在季节性低谷期间经常出现区域性消失，但由于其更强的传播性，麻疹更频繁地被重新传入。有人认为，这种重新传入的差异是麻疹和脊髓灰质炎在可根除性方面存在差异的关键决定因素。
