Estimation of the epidemic properties of the 2019 novel coronavirus: A mathematical modeling study

Jinghua Li; Yijing Wang; Stuart Gilmour; Mengying Wang; Daisuke Yoneoka; Ying Wang; Xinyi You; Jing Gu; Chun Hao; Liping Peng; Zhicheng Du; Dong Roman Xu; Yuantao Hao

This study estimated the basic reproduction number, " , for the 2019 novel coronavirus using confirmed cases from 10 th January -8 th February. We applied five methods to estimate " in order to ensure that our estimate was robust to differences in assumptions about epidemic processes, differences in assumed underlying parameters, and about the nature of the dynamics of the affected population. We estimated the basic reproduction number for the whole period to be 3.39 (95% CI: 3.09 -3.70), a very high number indicative of a very fast rate of spread. We also estimated the basic reproduction number separately for the pre-closure period, finding that in the first 13 days of available high-quality data on the epidemic that the basic reproduction number was 4.38 (95% CI: 3.63 -5.13), a very high number indicative of a highly infectious disease. Compared to this, we calculated the postclosure value of " to be 3.41 (95% CI: 3.16 -3.65), still a very high number but significantly lower than that observed in the earlier days of the epidemic. This lower basic reproduction number, and the recent apparent reduction in numbers of new infections, justifies the decision to close Wuhan city, and also shows the potentially high impact of self-quarantine and voluntary exclusion methods. A separate study (not published) conducted by one of the study authors found that 25% of students in Guangdong did not leave their home in the Chinese New Year period, 90% increased their handwashing frequency, and over 80% used a mask when moving in public places. These voluntary measures, combined with the closure of Wuhan city, may have averted the spread of this disease and reduced its ability to reproduce through social changes. The reduction in infectiousness is particularly striking given the huge movement of people that typically occurs during Chinese New Year, and the risk of exposure in public transport and family gatherings at this time.