Jiangsu Provincial Center for Disease Control and Prevention, Nanjing, China.
J Infect Dev Ctries. 2020 Dec 31;14(12):1361-1367. doi: 10.3855/jidc.13256.
The secondary attack rate (SAR) measures the transmissibility of an infectious agent. The reported SAR of COVID-19 varied in a broad range, and between different contact settings.
We conducted a meta-analysis on the SAR of COVID-19 with adherence to the PRISMA guideline. We searched published literatures and preprints in international databases of PubMed and medRxiv, and in five major Chinese databases as of 20 April 2020, using the following search terms: ("COVID-19" and "secondary attack rate") or ("COVID-19" and "close contact"). The random effect model was chosen for pooled analyses, using R (version 3.6.3).
A total of 1,136 references were retrieved and 18 of them remained after screening. The pooled SAR of COVID-19 was 0.07 (95%: 0.03-0.12) in general. It differed significantly between contact settings, peaking in households (0.20, 95%: 0.15-0.28), followed by in social gatherings (0.06, 95%: 0.03-0.10). The point estimates of the pooled SARs in health facilities, transports, and work/study settings were all as low as 0.01. Among all the secondary cases, the proportion of asymptomatic infections was estimated to be 0.17 (95% CI: 0.09 - 0.34). The proportion was higher in households (0.26, 95% CI: 0.12-0.56), than in other contact settings.
The transmission risk of SARS-CoV-2 is much higher in households than in other scenarios. Identification of asymptomatic secondary infections should be enhanced in households.
继发感染率（SAR）用于衡量传染病的传染性。COVID-19 的报道 SAR 变化范围广泛，且在不同接触环境中也有所不同。
我们按照 PRISMA 指南对 COVID-19 的 SAR 进行了荟萃分析。我们检索了国际数据库 PubMed 和 medRxiv 中已发表的文献和预印本，以及截至 2020 年 4 月 20 日的五个主要中文数据库，使用以下搜索词：（“COVID-19”和“继发感染率”）或（“COVID-19”和“密切接触”）。采用 R（版本 3.6.3）进行汇总分析，选择随机效应模型。
共检索到 1136 篇参考文献，筛选后保留了 18 篇。COVID-19 的总体 SAR 为 0.07（95%：0.03-0.12）。接触环境不同，SAR 差异显著，家庭中最高（0.20，95%：0.15-0.28），其次是社交聚会（0.06，95%：0.03-0.10）。卫生保健机构、交通和工作/学习环境中 SAR 的点估计均低至 0.01。在所有继发病例中，无症状感染的比例估计为 0.17（95% CI：0.09-0.34）。家庭中的比例（0.26，95% CI：0.12-0.56）高于其他接触环境。
SARS-CoV-2 的传播风险在家庭中比在其他环境中高得多。应加强家庭中无症状继发感染的识别。
