What is Required to Prevent a Second Major Outbreak of the Novel Coronavirus COVID-19 Upon Lifting the Metropolitan-Wide Quarantine of Wuhan City, China: A Mathematical Modelling Study

Background: The Chinese government implemented a metropolitan-wide quarantine of Wuhan city on 23 rd January 2020 to curb the epidemic of the coronavirus COVID-19. Lifting of this quarantine is imminent. We modelled the effects of two key health interventions on the epidemic when the quarantine is lifted.Method: We constructed a compartmental dynamic model to forecast the trend of the COVID-19 epidemic at different quarantine lifting dates and investigated the impact of different rates of public contact and facial mask usage on the epidemic.Results: We projected a declining trend of the COVID-19 epidemic if the current quarantine strategy continues, and Wuhan would record the last new confirmed cases on 25 th April 2020. At the end of the epidemic, 65,572 (46,156-95,264) individuals would be infected by the virus, among which 16,144 (14,422-23,447, 24.6%) were through public contacts, 45,795 (32,390-66,395, 69.7%) through household contact, and 3,633 (2,344-5,865, 5.5%) through hospital contacts (including 783 (553-1,134) non-COVID-19 patients and 2,850 (1,801-4,981) medical staff). A total of 3,262 (1,592-6,470) would die of COVID-19 related pneumonia in Wuhan. Early quarantine lifting on 21 st March is viable only if Wuhan residents sustain a high facial mask usage of ≥85% and a pre-quarantine level public contact rate. Delaying city resumption to mid/late April would relax the requirement of facial mask usage to ≥75% at the same contact rate.Conclusion: The prevention of a second epidemic is viable after the metropolitan-wide quarantine is lifted but requires a sustaining high facial mask usage and a low public contact rate.Funding Statement: This work is supported by a Research Grant from the Bill & Melinda Gates Foundation. Declaration of Interests: None.