Department of Zoology, Oxford University, Oxford, UK.
Epidemiol Infect. 2012 Dec;140(12):2290-301. doi: 10.1017/S0950268812000131. Epub 2012 Feb 16.
Childhood rubella infection in early pregnancy can lead to fetal death or congenital rubella syndrome (CRS) with multiple disabilities. Reduction of transmission via universal vaccination can prevent CRS, but inadequate coverage may increase CRS numbers by increasing the average age at infection. Consequently, many countries do not vaccinate against rubella. The World Health Organization recommends that for safe rubella vaccination, at least 80% coverage of each birth cohort should be sustained. The nonlinear relationship between CRS burden and infection dynamics has been much studied; however, how the complex interaction between epidemic and demographic dynamics affects minimum safe levels of coverage has not been quantitatively evaluated across scales necessary for a global assessment. We modelled 30-year CRS burdens across epidemiological and demographic settings, including the effect of local interruption of transmission via stochastic fadeout. Necessary minimum vaccination coverage increases markedly with birth and transmission rates, independent of amplitude of seasonal fluctuations in transmission. Susceptible build-up in older age groups following local stochastic extinction of rubella increased CRS burden, indicating that spatial context is important. In low birth-rate settings, 80% routine coverage is a conservative guideline, particularly if supplemented with campaigns and vaccination of women of childbearing age. Where birth and transmission rates are high, immunization coverage must be well above 80% and campaigns may be needed. Policy-makers should be aware of the potential negative effect of local extinction of rubella, since heterogeneity in vaccination coverage will shape extinction patterns, potentially increasing CRS burdens.
儿童在妊娠早期感染风疹会导致胎儿死亡或先天性风疹综合征（CRS），伴有多种残疾。通过普遍接种疫苗可以减少传播，但由于感染平均年龄的增加，接种率不足可能会导致 CRS 病例数增加。因此，许多国家不接种风疹疫苗。世界卫生组织建议，为了安全接种风疹疫苗，每个出生队列至少应保持 80%的覆盖率。CRS 负担与感染动态之间的非线性关系已经得到了广泛研究；然而，流行病和人口动态之间的复杂相互作用如何影响覆盖范围的最小安全水平，还没有在全球评估所需的各种规模上进行定量评估。我们对包括通过随机衰减中断局部传播的效果在内的 30 年 CRS 负担进行了建模，在不同的流行病学和人口统计学环境中进行了建模。接种覆盖率的最低必要值随着出生率和传播率的增加而显著增加，而与传播季节性波动的幅度无关。在局部随机消灭风疹后，年龄较大的人群中易感人群的增加增加了 CRS 的负担，这表明空间背景很重要。在低出生率环境中，80%的常规覆盖率是一个保守的指导方针，特别是如果辅以针对育龄妇女的运动和接种。在出生率和传播率较高的情况下，免疫接种覆盖率必须远远高于 80%，可能需要开展运动。政策制定者应该意识到风疹局部灭绝的潜在负面影响，因为接种覆盖率的异质性将塑造灭绝模式，可能会增加 CRS 的负担。
