Introduction

Methods

Results and discussion

Conclusion

Acknowledgements

References

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, R0, 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 (g), we estimated R0 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 R0 ranges from 2.24 (95%CI: 1.96–۲٫۵۵)to 3.58 (95%CI: 2.89–۴٫۳۹) associated with 8-fold to 2-fold increase in the reporting rate. We demonstrated that changes in reporting rate substantially affect estimates of R0. Conclusion: The mean estimate of R0 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

Introduction

The atypical pneumonia case, caused by a novel coronavirus (2019-nCoV), was first reported and confirmed in Wuhan, China on December31,2019(WorldHealthOrganization,2020a).AsofJanuary 26(17:00 GMT), 2020,therehavebeen2033 confirmedcasesof2019- nCoV infections in mainland China, including 56 deaths (National Health Commission of the People’s Republic of China, 2020). The 2019-nCoV cases were also reported in Thailand, Japan, Republic of Korea, Hong Kong, Taiwan and the US, and all of these cases were exported from Wuhan; see the World Health Organization (WHO) news release https://www.who.int/csr/don/en/ from January 14–۲۱٫ The outbreak is still ongoing. A recently published preprint by Imai et al. estimated that a total of 1723 (95% CI: 427-4471) cases of 2019- nCoV infections inWuhanhad onsetof symptoms by January 12,2020 (Imai et al., 2020). The likelihood of travel related risks of disease spreading is suggested by Bogoch et al. (2020), which indicates the potentials of regional and global spread (Leung et al., 2020).

To the best of our knowledge,there is no existing peer-reviewed literature quantifying the transmissibility of 2019-nCoV as of January 22, 2020. In this study, we estimated the transmissibility of 2019-nCoV via the basic reproduction number, R0, based on the limited data in the early phase of the outbreak.