SS and RK would like to acknowledge funding from DARPA (HR0011938513). CX acknowledges the support from the Laboratory Directed Research and Development (LDRD) Program at Los Alamos National Laboratory. The funders
had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
The novel coronavirus (2019-nCoV) is a recently emerged human
pathogen that has spread widely since January 2020. Initially, the basic reproductive number, R0, was estimated to be 2.2 to 2.7. Here we provide a new estimate of this quantity. We collected extensive individual case reports and estimated key epidemiology
parameters, including the incubation period. Integrating these estimates and high-resolution real-time human travel and infection data with mathematical models, we estimated that the number of infected individuals during early epidemic double every 2.4 days,
and the R0 value is likely to be between 4.7 and 6.6. We further show that quarantine and contact tracing of symptomatic individuals alone may not be effective and early, strong control measures are needed to stop transmission of the virus.