Estimating the Number of 2019 Novel Coronavirus Cases in Chinese Mainland

Background: An outbreak of clusters of viral pneumonia due to 2019 novel Coronavirus (2019-nCoV) happened in Wuhan, Hubei province in China in December 2019. Since the outbreak, 2 studies estimated the possible epidemic trend of the infection, but proved to be inconsistent with the actual confirmed number of cases. We intend to re-estimate the trend and peak arrival time for the 2019-nCoV infection transmission in Chinese mainland using the SEIR model, so as to provide theoretical basis for future prevention and control of the current epidemic in China. Methods: An infectious disease dynamics SEIR model was applied to forecast the epidemic’s development trend in China from 26 January 2020 based on data collected from the database reported by the National Health Commission. R0 were assumed to be 0.5, 0.25 and 0.125. Findings: The estimated numbers of cumulative cases would reach the peak on 3rd, 4th and 5th of February, 2020, which were 11,116, 11,373, 11,966, respectively, in Chinese Mainland. Similar peaks were also identified in Hubei Province, Wuhan City and other locations of China outside Hubei Province. The epidemic of 2019 novel Coronavirus was estimated to subside between early May (R0 = 0.125) and early August (R0 = 0.5). The estimated average number of deaths ranged from 344 to 1146. Interpretation: 2019-nCoV may be a virus of a high infectivity. The all-out efforts from Chinese government to prevent and control the infection are effective so far, but rigorous measures should be maintained to prevent further spread of the virus. Funding Statement: This work is funded by the National Key Research and Development Project (2018YFC1705100, 2018YFC1705103) and the National Natural Science Foundation of China (71673187). Declaration of Interests: All authors declare no competing interests. Ethics Approval Statement: Not required.