key: cord-309569-b9jcgx4s
authors: Lin, Qiu-Shi; Hu, Tao-Jun; Zhou, Xiao-Hua
title: Further explanations for the eq. (3) in “Estimating the daily trend in the size of the COVID-19 infected population in Wuhan”
date: 2020-09-15
journal: Infect Dis Poverty
DOI: 10.1186/s40249-020-00749-5
sha: 
doc_id: 309569
cord_uid: b9jcgx4s

To avoid possible confusions to the readers, we provide further explanations for the eq. (3) in the research article “Estimating the daily trend in the size of the COVID-19 infected population in Wuhan” published in the Infectious Diseases of Poverty.

In our study [1] , we proposed a new model to estimate the daily trend in the size of the COVID-19 infected population in Wuhan. When discussing this article with our colleagues, we found that a little more explanations for eq.

(3) are needed to avoid possible confusions to the readers.

In the Methods section, we let x t be the number of imported cases outside Hubei province on Day t, and derive a binomial model

To make our model clearer, here x t is in fact the number of infected individuals that travelled from Wuhan to places outside Hubei province on Day t − d. However, among the 10 940 confirmed cases in our data, 8546 (78.1%) do not have information on the date of departure from Wuhan, so the number of cases leaving Wuhan every day is unknown and hard to impute.

But the date of confirmation is available for each of the 10 940 cases, so we use the cumulative number of imported cases outside Hubei province as of Day t as ap-

x k . Since the window from infection to detection is assumed as d days in our model, the infected cases that left Wuhan before Day t − d should be confirmed outside Hubei province before Day t, thus this approximation is reasonable and would not affect the conclusion in the paper.

Estimating the daily trend in the size of the COVID-19 infected population in Wuhan

None.Authors' contributions QL, TH, and XZ interpreted the results and wrote the manuscript. All authors read and approved the final manuscript.

Not applicable. 

The authors declare that they have no competing interests. Received: 3 August 2020 Accepted: 1 September 2020