Estimating the Unreported Number of Novel Coronavirus (2019-nCoV) Cases in China in the First Half of January 2020: A Data-Driven Modelling Analysis of the Early Outbreak.

Shi Zhao,Daihai He,Lin Yang,Maggie H Wang,Daozhou Gao,Jinjun Ran,Qianying Lin,Guangpu Yang,Salihu S Musa,Yijun Lou,Weiming Wang

doi:10.3390/jcm9020388

Abstract

Background: In December 2019, an outbreak of respiratory illness caused by a novel coronavirus (2019-nCoV) emerged in Wuhan, China and has swiftly spread to other parts of China and a number of foreign countries. The 2019-nCoV cases might have been under-reported roughly from 1 to 15 January 2020, and thus we estimated the number of unreported cases and the basic reproduction number, R0, of 2019-nCoV. Methods: We modelled the epidemic curve of 2019-nCoV cases, in mainland China from 1 December 2019 to 24 January 2020 through the exponential growth. The number of unreported cases was determined by the maximum likelihood estimation. We used the serial intervals (SI) of infection caused by two other well-known coronaviruses (CoV), Severe Acute Respiratory Syndrome (SARS) and Middle East Respiratory Syndrome (MERS) CoVs, as approximations of the unknown SI for 2019-nCoV to estimate R0. Results: We confirmed that the initial growth phase followed an exponential growth pattern. The under-reporting was likely to have resulted in 469 (95% CI: 403–540) unreported cases from 1 to 15 January 2020. The reporting rate after 17 January 2020 was likely to have increased 21-fold (95% CI: 18–25) in comparison to the situation from 1 to 17 January 2020 on average. We estimated the R0 of 2019-nCoV at 2.56 (95% CI: 2.49–2.63). Conclusion: The under-reporting was likely to have occurred during the first half of January 2020 and should be considered in future investigation.

Highlights

A novel coronavirus (2019-nCoV) infected pneumonia infection, which is deadly [1], was first identified in Wuhan, China in December 2019 [2]
The time series data of 2019-nCoV cases in mainland China were initially released by the Wuhan Municipal Health Commission from 10 to January 2020 [8], and later by the National Health Commission of China after January 2020 [9]
We modelled h(k) as Gamma distributions with mean of 8.0 days and standard deviation (SD) of 3.6 days by averaging the serial intervals (SI) mean and SD of Severe Acute Respiratory Syndrome (SARS), mean of 7.6 days and SD of 3.4 days [18], and Middle East Respiratory Syndrome (MERS), mean of 8.4 days and SD of 3.8 days [19]

Summary

Introduction

A novel coronavirus (2019-nCoV) infected pneumonia infection, which is deadly [1], was first identified in Wuhan, China in December 2019 [2]. Leung et al drew a similar conclusion and estimated the number of cases exported from Wuhan to other major cities in China [6], and the potentials of travel related risks of disease spreading was indicated by [7]. In December 2019, an outbreak of respiratory illness caused by a novel coronavirus (2019-nCoV) emerged in Wuhan, China and has swiftly spread to other parts of China and a number of foreign countries. The 2019-nCoV cases might have been under-reported roughly from 1 to 15 January 2020, and we estimated the number of unreported cases and the basic reproduction number, R0, of 2019-nCoV. The under-reporting was likely to have resulted in 469 (95% CI: 403–540) unreported cases from 1 to 15 January 2020. Conclusion: The under-reporting was likely to have occurred during the first half of January 2020 and should be considered in future investigation

Objectives

Results

Conclusion