An updated estimation of the risk of transmission of the novel coronavirus (2019-nCov)

Tang, Biao; Bragazzi, Nicola Luigi; Li, Qian; Tang, Sanyi; Xiao, Yanni; Wu, Jianhong

Within the existing literature, two studies estimated under-estimation of coronavirus cases: the investigations by Zhao and collaborators (Zhao et al., 2020) and by Read et al. (Read, Bridgen, Cummings, Ho, & Jewell, 2020) . Specifically, Zhao and coworkers (Zhao et al., 2020) have assessed from a quantitative standpoint the under-reporting rate of coronavirus cases, modeling the epidemic growth curve using the exponential growing Poisson process. Authors computed the number of under-reported coronavirus cases to be 469 (95% CI 403e540). Based on this estimate, the basic reproduction number was found to be 2.56 (95% CI 2.49e2.63). In a previous version of the investigation, released in the bioRxiv pre-print server, the reproduction number was computed to oscillate between 3.30 (95% CI 2.73e3.96) and 5.47 (95% CI 4.16e7.10). The basic reproduction number was also found to be associated with 0-folde2-fold increase in the reporting rate. More in detail, with report rates increasing over the time, the mean value was statistically likely to be higher than 3 but less than 5. Read and coauthors (Read et al., 2020) used a deterministic SEIR model, assuming coronavirus cases being Poisson distributed and with parameter inference being achieved by maximum likelihood estimation utilizing the Nelder-Mead optimization approach. According to the dynamics transmission model, an ascertainment rate of 5.0% (95% CI 3.6e7.4) was computed and, based on this, authors estimated that as of January 22nd , 2020 in Wuhan there were 14,464 (95% CI 6510e25095) infected individuals, and 21,022 (95% CI 11,090e33,490) infections. The basic reproduction number was computed to be 3.11 (95% CI 2.39e4.13). In terms of public health implications, in order to stop the outbreak, at least 58e76% of transmissions should be blocked.