The time scale of asymptomatic transmission affects estimates of epidemic potential in the COVID-19 outbreak
The time scale of asymptomatic transmission affects estimates of epidemic potential in the COVID-19 outbreak
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DOI：
10.1016/j.epidem.2020.100392
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发表时间：
2020-06-01
期刊：
影响因子：
3.8
通讯作者：
Weitz, Joshua S.
中科院分区：
文献类型：
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作者：
Park, Sang Woo;Cornforth, Daniel M.;Weitz, Joshua S.
无症状携带者在传播中的作用为COVID-19大流行的控制带来了挑战。目前正在研究无症状传播及其对监测和疾病负担的影响，但关于无症状传播对疾病动态的影响的研究很少。我们使用一个数学框架来评估无症状传播对基本繁殖数R-0（即，完全易感人群中平均原发病例产生的继发病例的预期数量）和可归因于无症状个体的新发继发病例的比例。如果无症状传播的世代间隔分布不同于有症状传播的世代间隔分布，那么没有明确说明无症状病例的基本繁殖数的估计可能存在系统性偏差。具体而言，如果无症状病例的世代间隔比有症状病例短，则R-0将被高估，如果它们的世代间隔较长，则R-0将被低估。在指数阶段无症状传播的实现比例的估计也取决于无症状的世代间隔。我们的分析表明，了解无症状传播的时间过程对于评估这种传播途径的重要性和疾病动态非常重要。这为调查无症状传播的重要性和相对持续时间提供了额外的动机。
The role of asymptomatic carriers in transmission poses challenges for control of the COVID-19 pandemic. Study of asymptomatic transmission and implications for surveillance and disease burden are ongoing, but there has been little study of the implications of asymptomatic transmission on dynamics of disease. We use a mathematical framework to evaluate expected effects of asymptomatic transmission on the basic reproduction number R-0 (i.e., the expected number of secondary cases generated by an average primary case in a fully susceptible population) and the fraction of new secondary cases attributable to asymptomatic individuals. If the generation-interval distribution of asymptomatic transmission differs from that of symptomatic transmission, then estimates of the basic reproduction number which do not explicitly account for asymptomatic cases may be systematically biased. Specifically, if asymptomatic cases have a shorter generation interval than symptomatic cases, R-0 will be over-estimated, and if they have a longer generation interval, R-0 will be under-estimated. Estimates of the realized proportion of asymptomatic transmission during the exponential phase also depend on asymptomatic generation intervals. Our analysis shows that understanding the temporal course of asymptomatic transmission can be important for assessing the importance of this route of transmission, and for disease dynamics. This provides an additional motivation for investigating both the importance and relative duration of asymptomatic transmission.