Rapid communication Pattern of early human-to-human transmission of Wuhan 2019 novel coronavirus (2019-nCoV), December 2019 to January 2020 Julien Riou1 , Christian L. Althaus1 1. Institute of Social and Preventive Medicine, University of Bern, Bern, Switzerland Correspondence: Julien Riou (
[email protected]) Citation style for this article: Riou Julien , Althaus Christian L. Pattern of early human-to-human transmission of Wuhan 2019 novel coronavirus (2019-nCoV), December 2019 to January 2020. Euro Surveill. 2020;25(4):pii=2000058. https://doi.org/10.2807/1560-7917.ES.2020.25.4.2000058 Article submitted on 24 Jan 2020 / accepted on 30 Jan 2020 / published on 30 Jan 2020 Since December 2019, China has been experiencing Epidemic parameters a large outbreak of a novel coronavirus (2019-nCoV) Two key properties will determine further spread which can cause respiratory disease and severe pneu- of 2019-nCoV. Firstly, the basic reproduction num- monia. We estimated the basic reproduction num- ber R0 describes the average number of secondary ber R0 of 2019-nCoV to be around 2.2 (90% high density cases generated by an infectious index case in a fully interval: 1.4–3.8), indicating the potential for sus- susceptible population, as was the case during the tained human-to-human transmission. Transmission early phase of the outbreak. If R0 is above the critical characteristics appear to be of similar magnitude to threshold of 1, continuous human-to-human transmis- severe acute respiratory syndrome-related coronavi- sion with sustained transmission chains will occur. rus (SARS-CoV) and pandemic influenza, indicating a Secondly, the individual variation in the number of risk of global spread.