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Meta-Analysis
. 2021 Sep 17;10(1):119.
doi: 10.1186/s40249-021-00901-9.

The incubation period of COVID-19: a global meta-analysis of 53 studies and a Chinese observation study of 11 545 patients

Cheng Cheng  1 , DongDong Zhang  2 , Dejian Dang  3 , Juan Geng  1 , Peiyu Zhu  1 , Mingzhu Yuan  1 , Ruonan Liang  1 , Haiyan Yang  1 , Yuefei Jin  1 , Jing Xie  4   5 , Shuaiyin Chen  6 , Guangcai Duan  7   8
Affiliations
Meta-Analysis

The incubation period of COVID-19: a global meta-analysis of 53 studies and a Chinese observation study of 11 545 patients

Cheng Cheng et al. Infect Dis Poverty. .

Abstract

Background: The incubation period is a crucial index of epidemiology in understanding the spread of the emerging Coronavirus disease 2019 (COVID-19). In this study, we aimed to describe the incubation period of COVID-19 globally and in the mainland of China.

Methods: The searched studies were published from December 1, 2019 to May 26, 2021 in CNKI, Wanfang, PubMed, and Embase databases. A random-effect model was used to pool the mean incubation period. Meta-regression was used to explore the sources of heterogeneity. Meanwhile, we collected 11 545 patients in the mainland of China outside Hubei from January 19, 2020 to September 21, 2020. The incubation period fitted with the Log-normal model by the coarseDataTools package.

Results: A total of 3235 articles were searched, 53 of which were included in the meta-analysis. The pooled mean incubation period of COVID-19 was 6.0 days (95% confidence interval [CI] 5.6-6.5) globally, 6.5 days (95% CI 6.1-6.9) in the mainland of China, and 4.6 days (95% CI 4.1-5.1) outside the mainland of China (P = 0.006). The incubation period varied with age (P = 0.005). Meanwhile, in 11 545 patients, the mean incubation period was 7.1 days (95% CI 7.0-7.2), which was similar to the finding in our meta-analysis.

Conclusions: For COVID-19, the mean incubation period was 6.0 days globally but near 7.0 days in the mainland of China, which will help identify the time of infection and make disease control decisions. Furthermore, attention should also be paid to the region- or age-specific incubation period.

Keywords: COVID-19; Incubation period; Meta-analysis.

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Conflict of interest statement

The authors declare that they have no competing interests.

Figures

Fig. 1
Fig. 1
The flowchart of meta-analysis
Fig. 2
Fig. 2
The Forest plot for study-specific mean incubation period of Coronavirus disease 2019. CI confidence interval
Fig. 3
Fig. 3
The fitted distribution of incubation period of Coronavirus disease 2019
Fig. 4
Fig. 4
The histogram of individual incubation period of Coronavirus disease 2019 in the 218 patients with precise data
See this image and copyright information in PMC

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