Changes in reporting likely occurred and should be taken into account in the estimation of R 0 .

We estimated that the mean R 0 ranges from 2.24 to 3.58 with an 8-fold to 2-fold increase in the reporting rate.

We aim to estimate the basic reproduction number of 2019-nCoV in Wuhan, China using the exponential growth model method.

Abstract

Backgrounds An ongoing outbreak of a novel coronavirus (2019-nCoV) pneumonia hit a major city in China, Wuhan, December 2019 and subsequently reached other provinces/regions of China and other countries. We present estimates of the basic reproduction number, R 0 , of 2019-nCoV in the early phase of the outbreak.

Methods Accounting for the impact of the variations in disease reporting rate, we modelled the epidemic curve of 2019-nCoV cases time series, in mainland China from January 10 to January 24, 2020, through the exponential growth. With the estimated intrinsic growth rate (γ), we estimated R 0 by using the serial intervals (SI) of two other well-known coronavirus diseases, MERS and SARS, as approximations for the true unknown SI.

Findings The early outbreak data largely follows the exponential growth. We estimated that the mean R 0 ranges from 2.24 (95%CI: 1.96–2.55) to 3.58 (95%CI: 2.89–4.39) associated with 8-fold to 2-fold increase in the reporting rate. We demonstrated that changes in reporting rate substantially affect estimates of R 0 .