Pattern of early human-to-human transmission of Wuhan 2019-nCoV

Julien Riou; Christian L. Althaus

Our analysis, while limited due to the scarcity of data, has two important strengths. First, it is based on the simulation of a wide range of possibilities regarding epidemic parameters and allows for the full propagation of the many remaining uncertainties regarding 2019-nCoV and the situation in Wuhan: the size of the initial zoonotic event at the wet market, the date(s) of the initial animal-to-human transmission event(s) and the generation time interval. While accounting for all these uncertainties, our analysis provides a reliable summary of the current state of knowledge about the human-to-human transmissibility of 2019-nCoV. Second, its focus on the possibility of superspreading events by using negative-binomial offspring distributions is very important in the context of emerging coronaviruses [4, 5] . While our estimate of k remains very imprecise, the simulations suggest that very low values of k (< 0.1) are less likely than higher values (> 1) that correspond to a more homogeneous transmission pattern. However, values of k in the range of 0.1-0.2 are still compatible with the occurrence of large superspreading events, especially in hospital settings [15, 16] .