The Novel Coronavirus, 2019-nCoV, is Highly Contagious and More Infectious Than Initially Estimated

Steven Sanche; Yen Ting Lin; Chonggang Xu; Ethan Romero-Severson; Nick Hengartner; Ruian Ke

The 2019-nCoV epidemic is still rapidly growing and spread to more than 20 countries as of February 5, 2020. Here, we estimated the growth rate of the early outbreak in Wuhan to be 0.29 per day (a doubling time of 2.4 days), and the reproductive number, R0, to be between 4.7 to 6.6 (CI: 2.8 to 11.3). Among many factors, the Lunar New Year Travel rush in early and mid-January 2020 may or may not play a role in the high outbreak growth rate, although SARS epidemic also overlapped with the Lunar New Year Travel rush. How contiguous the 2019-nCoV is in other countries remains to be seen. If the value of R0 is as high in other countries, our results suggest that active and strong population-wide social distancing efforts, such as closing down transportation system, schools, discouraging travel, etc., might be needed to reduce the overall contacts to contain the spread of the virus. , between hospitalization to discharge (E) and between hospitalization to death (F). Filled circles and bars on x-axes denote the estimated mean and 95% confidence intervals. Histograms and the means (stars) of estimated R0 assuming individuals become infectious at symptom onset (blue) or 2 days before symptom onset (orange). The dotted line denotes R0=1. (B) The levels of minimum efforts (lines) of intervention strategies needed to control the virus spread. Strategies considered are quarantine of symptomatic individuals and individuals who had contacts with them (x-axis) and population-level efforts to reduce overall contact rates (y-axis). Different colored lines denote different assumptions of the fraction of asymptomatic individuals in the infected population. Solid and dashed lines correspond to R 0 =4.7 and 6.3 (i.e. the estimated means of R0), respectively. (C) The cumulative number of cases outside of Hubei province in late January 2020. The growth rate decreased to 0.14 per day since January 30. The dashed black line shows January 23 when Wuhan is locked down.