Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA.
Welch Medical Library, Johns Hopkins University, Baltimore, MD, USA.
Epidemiol Infect. 2024 Oct 8;152:e121. doi: 10.1017/S0950268824000955.
SARS-CoV-2 superspreading occurs when transmission is highly efficient and/or an individual infects many others, contributing to rapid spread. To better quantify heterogeneity in SARS-CoV-2 transmission, particularly superspreading, we performed a systematic review of transmission events with data on secondary attack rates or contact tracing of individual index cases published before September 2021 prior to the emergence of variants of concern and widespread vaccination. We reviewed 592 distinct events and 9,883 index cases from 491 papers. A meta-analysis of secondary attack rates identified substantial heterogeneity across 12 chosen event types/settings, with the highest transmission (25-35%) in co-living situations including households, nursing homes, and other congregate housing. Among index cases, 67% reported zero secondary cases and only 3% (287) infected >5 secondary cases ("superspreaders"). Index case demographic data were limited, with only 55% of individuals reporting age, sex, symptoms, real-time polymerase chain reaction (PCR) cycle threshold values, or total contacts. With the data available, we identified a higher percentage of superspreaders among symptomatic individuals, individuals aged 49-64 years, and individuals with over 100 total contacts. Addressing gaps in the literature regarding transmission events and contact tracing is needed to properly explain the heterogeneity in transmission and facilitate control efforts for SARS-CoV-2 and other infections.
SARS-CoV-2 的超级传播事件是指当传播效率非常高且/或个体感染了大量其他人时，从而导致快速传播。为了更好地量化 SARS-CoV-2 传播中的异质性，特别是超级传播事件，我们对截至 2021 年 9 月之前在出现关注变体和广泛疫苗接种之前，在出版物中发表的有关二次攻击率或个体索引病例接触者追踪的传播事件进行了系统回顾。我们回顾了 491 篇论文中的 592 个不同事件和 9883 个索引病例。对二次攻击率的荟萃分析确定了 12 种选定的事件类型/环境中存在大量异质性，在包括家庭、疗养院和其他集体住房在内的共同居住环境中传播率最高（25-35%）。在索引病例中，67%报告没有二次感染病例，只有 3%（287 例）感染了超过 5 个二次感染病例（“超级传播者”）。索引病例的人口统计学数据有限，只有 55%的个体报告了年龄、性别、症状、实时聚合酶链反应（PCR）循环阈值或总接触者。根据现有数据，我们发现有症状的个体、49-64 岁的个体以及总接触者超过 100 人的个体中，超级传播者的比例更高。需要解决文献中关于传播事件和接触者追踪的空白，以正确解释传播中的异质性，并促进对 SARS-CoV-2 和其他感染的控制工作。
