Epidemiological parameters of coronavirus disease 2019: a pooled analysis of publicly reported individual data of 1155 cases from seven countries

Shujuan Ma; Jiayue Zhang; Minyan Zeng; Qingping Yun; Wei Guo; Yixiang Zheng; Shi Zhao; Maggie H Wang; Zuyao Yang

where r is exponential growth rate, μ is mean serial interval, σ is standard deviation of serial interval, 1/a is latent period, and 1/b is infectious period. The exponential growth rate was obtained directly from a previous study reporting incidence data of the early stage of epidemic, 1 while the other parameters came from the present study. The latent period was approximated by the upper limit of latent period, and the infectious period was approximated as serial interval minus the upper limit of latent period. Although the true value of latent period was bound to be smaller than the upper limit, we argued that this would not exert a significant impact on the estimation of R0 according to the above formula (2), because when the latent period became shorter the infectious period would become longer accordingly, given a fixed serial interval.