Feasibility of Controlling COVID-19 Outbreaks in the UK by Rolling Interventions

Po Yang; Jun Qi; Shuhao Zhang; Gaoshan Bi; Xulong Wang; Yun Yang; Bin Sheng; Xuxin Mao

The model accounted for delays in symptom onset and reporting by including compartments to reflect transitions between reporting states and disease states. Here, this modal assumed that S is initial susceptible population of certain region; and incorporated an initial intervention of surveillance and isolation of cases in contain phase by a parameter β. 14.15 If effectiveness of intervention in contain phase was not sufficiently strong, susceptible individuals may contract disease with a given rate when in contact with a portion of exposed population E. After an incubation period α 1 , the exposed individuals became the infectious population I at a ratio 1/α 1 .The incubation period was assumed to be 5.8 days. 8 Once exposed to infection, infectious population started from Mild cases M to Critical cases C at a ratio a, Critical cases led to deaths at a ratio d; other infectious population finally recovered. We assumed that COVID-19 can be initially detected in 2 days prior to symptom onset and persist for 7 days in moderate cases and 14 days to severe cases. 19 Figure 2 : Extended SEMCR model structure: The population is divided into the following six classes: susceptible, exposed (and not yet symptomatic), infectious (symptomatic), mild (mild or moderate symptom), critical (severe symptom), death and recovered (i.e, isolated, recovered, or otherwise non-infectious).