Background

Large norovirus (NoV) outbreaks are explosive in nature and vary widely in final size and duration, suggesting that superspreading combined with heterogeneous contact may explain these dynamics. Modeling tools that can capture heterogeneity in infectiousness and contact are important for NoV outbreak prevention and control, yet they remain limited.

Methods

Data from a large NoV outbreak at a Dutch scout jamboree, which resulted in illness among 326 (of 4500 total) individuals from 7 separate camps, were used to examine the contributions of individual variation in infectiousness and clustered contact patterns to the transmission dynamics. A Bayesian hierarchical model of heterogeneous, clustered outbreak transmission was applied to represent (1) between-individual heterogeneity in infectiousness and (2) heterogeneous patterns of contact.

Results

We found wide heterogeneity in infectiousness across individuals, suggestive of superspreading. Nearly 50% of individual infectiousness was concentrated in the individual’s subcamp of residence, with the remainder distributed over other subcamps. This suggests a source-and-sink dynamic in which subcamps with greater average infectiousness fed cases to those with a lower transmission rate. Although the per capita transmission rate within camps was significantly greater than that between camps, the large pool of susceptible individuals across camps enabled similar numbers of secondary cases generated between versus within camps.

Conclusions

The consideration of clustered transmission and heterogeneous infectiousness is important for understanding NoV transmission dynamics. Models including these mechanisms may be useful for providing early warning and guiding outbreak response.

中文翻译：

---

了解大型诺如病毒暴发的动力学中接触异质性和可变传染性的重要性

背景

大型诺如病毒（NoV）爆发本质上是爆炸性的，并且最终大小和持续时间差异很大，这表明超级传播与异构接触相结合可以解释这些动态。可以捕获传染性和接触性异质性的建模工具对于新病毒爆发的预防和控制很重要，但仍然受到限制。

方法

来自荷兰侦察兵大型暴发的一次新病毒暴发的数据，该数据导致来自7个不同营地的326名（共4,500名）个体患病，这些数据被用于检验个体感染力变异和聚集接触方式对传播动态的影响。贝叶斯异质，集群爆发传播的层次模型被用来表示（1）传染性之间的个体异质性和（2）接触的异质性模式。

结果

我们发现个体之间在传染性方面存在广泛的异质性，表明存在超级传播。个体感染力的近50％集中在个体居住的子营地，其余分布在其他子营地。这表明源和汇的动态，其中平均传染性较高的子营将病例传染给传播率较低的人。尽管难民营内的人均传播率大大高于难民营之间的人均传播率，但难民营之间的大量易感人群使在难民营之间和难民营内产生的继发病例数相似。

结论

群集传播和异构传染性的考虑对于理解新病毒传播动力学很重要。包括这些机制的模型对于提供预警和指导爆发反应可能有用。