Department of Physics, Ohio State University, Columbus, Ohio, United States of America.
PLoS One. 2021 Mar 25;16(3):e0248808. doi: 10.1371/journal.pone.0248808. eCollection 2021.
A number of epidemics, including the SARS-CoV-1 epidemic of 2002-2004, have been known to exhibit superspreading, in which a small fraction of infected individuals is responsible for the majority of new infections. The existence of superspreading implies a fat-tailed distribution of infectiousness (new secondary infections caused per day) among different individuals. Here, we present a simple method to estimate the variation in infectiousness by examining the variation in early-time growth rates of new cases among different subpopulations. We use this method to estimate the mean and variance in the infectiousness, β, for SARS-CoV-2 transmission during the early stages of the pandemic within the United States. We find that σβ/μβ ≳ 3.2, where μβ is the mean infectiousness and σβ its standard deviation, which implies pervasive superspreading. This result allows us to estimate that in the early stages of the pandemic in the USA, over 81% of new cases were a result of the top 10% of most infectious individuals.
一些传染病，包括 2002-2004 年的 SARS-CoV-1 疫情，已经被证实存在超级传播现象，即少数感染个体引发了大部分新感染。超级传播的存在意味着传染性（每天引起的新继发感染）在不同个体之间呈长尾分布。在这里，我们提出了一种简单的方法，通过检查不同亚群中新病例的早期增长率的变化来估计传染性的变化。我们使用这种方法来估计 SARS-CoV-2 在美国大流行早期的传播过程中β的均值和方差。我们发现，σβ/μβ≳3.2，其中μβ是平均传染性，σβ是其标准差，这意味着普遍存在超级传播。这一结果使我们能够估计，在美国大流行的早期阶段，超过 81%的新病例是由传染性最强的 10%的个体引起的。
