Preliminary estimation of the basic reproduction number of novel coronavirus (2019-nCoV) in China, from 2019 to 2020: A data-driven analysis in the early phase of the outbreak

Highlights

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  The novel coronavirus (2019-nCoV) pneumonia has caused 2033 confirmed cases, including 56 deaths in mainland China, by 2020-01-26 17:06.

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

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  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.

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

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.

Conclusion

The mean estimate of R ₀ for the 2019-nCoV ranges from 2.24 to 3.58, and is significantly larger than 1. Our findings indicate the potential of 2019-nCoV to cause outbreaks.