%0 Journal Article
%@ 1438-8871
%I JMIR Publications
%V 22
%N 10
%P e19994
%T Epidemiological Parameters of COVID-19: Case Series Study
%A Ma,Shujuan
%A Zhang,Jiayue
%A Zeng,Minyan
%A Yun,Qingping
%A Guo,Wei
%A Zheng,Yixiang
%A Zhao,Shi
%A Wang,Maggie H
%A Yang,Zuyao
%+ JC School of Public Health and Primary Care, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, 852 2252 8739, zyang@cuhk.edu.hk
%K coronavirus disease 2019
%K COVID-19
%K incubation period
%K serial interval
%K basic reproduction number
%K presymptomatic transmission
%D 2020
%7 12.10.2020
%9 Original Paper
%J J Med Internet Res
%G English
%X Background: The estimates of several key epidemiological parameters of the COVID-19 pandemic are often based on small sample sizes or are inaccurate for various reasons. Objective: The aim of this study is to obtain more robust estimates of the incubation period, serial interval, frequency of presymptomatic transmission, and basic reproduction number (R0) of COVID-19 based on a large case series. Methods: We systematically retrieved and screened 20,658 reports of laboratory-confirmed COVID-19 cases released by the health authorities of China, Japan, and Singapore. In addition, 9942 publications were retrieved from PubMed and China National Knowledge Infrastructure (CNKI) through April 8, 2020. To be eligible, a report had to contain individual data that allowed for accurate estimation of at least one parameter. Widely used models such as gamma distributions were fitted to the data sets and the results with the best-fitting values were presented. Results: In total, 1591 cases were included for the final analysis. The mean incubation period (n=687) and mean serial interval (n=1015 pairs) were estimated to be 7.04 (SD 4.27) days and 6.49 (SD 4.90) days, respectively. In 40 cases (5.82%), the incubation period was longer than 14 days. In 32 infector-infectee pairs (3.15%), infectees’ symptom onsets occurred before those of infectors. Presymptomatic transmission occurred in 129 of 296 infector-infectee pairs (43.58%). R0 was estimated to be 1.85 (95% CI 1.37-2.60). Conclusions: This study provides robust estimates of several epidemiological parameters of COVID-19. The findings support the current practice of 14-day quarantine of persons with potential exposure, but also suggest the need for additional measures. Presymptomatic transmission together with the asymptomatic transmission reported by previous studies highlight the importance of adequate testing, strict quarantine, and social distancing. 
%M 33001833
%R 10.2196/19994
%U http://www.jmir.org/2020/10/e19994/
%U https://doi.org/10.2196/19994
%U http://www.ncbi.nlm.nih.gov/pubmed/33001833