Forecasting whether or not initial reports of disease will be followed by a severe epidemic is an important component of disease management. Standard epidemic risk estimates involve assuming that infections occur according to a branching process and correspond to the probability that the outbreak persists beyond the initial stochastic phase. However, an alternative assessment is to predict whether or not initial cases will lead to a severe epidemic in which available control resources are exceeded. We show how this risk can be estimated by considering three practically relevant potential definitions of a severe epidemic; namely, an outbreak in which: (i) a large number of hosts are infected simultaneously; (ii) a large total number of infections occur; and (iii) the pathogen remains in the population for a long period. We show that the probability of a severe epidemic under these definitions often coincides with the standard branching process estimate for the major epidemic probability. However, these practically relevant risk assessments can also be different from the major epidemic probability, as well as from each other. This holds in different epidemiological systems, highlighting that careful consideration of how to classify a severe epidemic is vital for accurate epidemic risk quantification.

中文翻译：

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爆发是否会超过可用的控制资源？使用严重流行病的实际定义估计入侵病原体的风险

预测最初的疾病报告之后是否会出现严重的流行病是疾病管理的一个重要组成部分。标准流行病风险估计涉及假设感染按照分支过程发生，并对应于爆发持续超过初始随机阶段的概率。然而，另一种评估是预测初始病例是否会导致超出可用控制资源的严重流行。我们展示了如何通过考虑严重流行病的三个实际相关的潜在定义来估计这种风险；即爆发，其中： (i) 大量宿主同时被感染；(ii) 发生大量感染；(iii) 病原体在人群中长期存在。我们表明，根据这些定义，严重流行病的概率通常与主要流行病概率的标准分支过程估计值一致。然而，这些实际相关的风险评估也可能与主要流行概率不同，也可能彼此不同。这适用于不同的流行病学系统，强调仔细考虑如何对严重流行病进行分类对于准确量化流行病风险至关重要。