Full-spectrum dynamics of the coronavirus disease outbreak in Wuhan, China: a modeling study of 32,583 laboratory-confirmed cases

Hao, Xingjie; Cheng, Shanshan; Wu, Degang; Wu, Tangchun; Lin, Xihong; Wang, Chaolong

Vigorous non-pharmaceutical interventions have largely suppressed the COVID-19 outbreak in Wuhan, China. We extended the susceptible-exposed-infectious-recovered model to study the transmission dynamics and evaluate the impact of interventions using 32,583 laboratory-confirmed cases from December 8, 2019 till March 8, 2020, accounting for presymptomatic infectiousness, and time-varying ascertainment rates, transmission rates, and population movements. The effective reproduction number R0 dropped from 3.54 (95% credible interval: 3.41-3.66) in the early outbreak to 0.27 (0.23-0.32) after full-scale multi-pronged interventions. By projection, the interventions reduced the total infections in Wuhan by 96.1% till March 8. Furthermore, we estimated that 87% infections (lower bound: 53%) were unascertained, potentially including asymptomatic and mild-symptomatic cases. The probability of resurgence was 0.33 and 0.06 based on models with 87% and 53% infections unascertained, respectively, assuming all interventions were lifted after 14 days of no ascertained infections. These results provide important implications for continuing surveillance and interventions to eventually contain the outbreak.