Modelling the epidemic trend of the 2019 novel coronavirus outbreak in China

Mingwang Shen; Zhihang Peng; Yanni Xiao; Lei Zhang

On 20 th January 2020. two local infections in the Chinese province of Guangdong with no direct visit to Wuhan were the first confirmed human-to-human transmission cases [3] . (Figure 1a ), corresponding to a fatality rate of 11.02% (9.26-12.78%). This is lower than the fatality rates of the Severe Acute Respiratory Syndrome (SARS) (14-15%) [4] and the Middle East Respiratory Syndrome (MERS) (34.4%) [5] , suggesting that 2019-nCov may be a less virulent strain in the coronavirus family. Besides, experiences from fighting the previous coronaviruses may have also added to the rapid response to the epidemic by the Chinese government and the international society. However, we acknowledge that in the early phase of the epidemic, the death cases are likely under-reported as many infected cases have not progressed to the critical stage. Timely diagnosis for quarantine and integrated interventions are essential for curbing the epidemic. If the current intervention continues, the number of infected individuals is expected to peak in early March 2020 (80 days since initiation) with a peak population size of 827 (421-1232) infectious individuals in China. The current duration from symptom onset to isolation is about six days. Our model indicates that every one-day reduction in this duration would reduce the peak population size by 72-84% and the cumulative infected cases and deaths both by 68-80% (Figure 1c,d) . Integrated interventions, such as the promotion of face mask use and reduction of travel, have been actively implemented. We estimate that every additional 10% decay in the transmission rate due to integrated interventions would reduce the peak population size by 20-47%, the cumulative infected cases and deaths both by 23-49% (Figure 1c,d) . Facing the rapidly rising epidemic, the Chinese government has timely amended the Law of the PRC on the Prevention and Treatment of Infectious Diseases on 20 th January 2020 to include the 2019-nCov as a class-B infection but manage it as a class-A infection due to its severity [8] . Consequently, more than 30,000 PCR-fluorescence probing detection kit for 2019-nCoV RNA has been distributed to designated diagnosis centres in Wuhan [9] . The Chinese government has also taken an unprecedented action of locking down Wuhan and its nearby Huangguang city in a bid to minimise person-to-person contact on 23 rd January 2020 [10] .