The focus and timing of COVID-19 pandemic control measures under healthcare resource constraints

Chen Wei; Zhengyang Wang; Zhichao Liang; Quanying Liu

A successful suppression is judged based on the reproduction number. The reproduction number is defined as the average number of new infections each patient generates. When the reproduction number is less than 1, the number of new cases decreases. If the reproduction number is greater than 1, the number of new cases would increase until the susceptible pool runs out 34 . At the beginning of an outbreak when every individual is susceptible, the basic reproduction number 0 can by calculated from Equation (12), given that the asymptomatic cases are not infectious. With the current model specifying timedependent parameters and 50% asymptomatic transmissibility, the average time of contact for the symptomatic and asymptomatic cohort is computed respectively in Equation (13) and Equation (14) . A daily reproduction number is then computed as in Equation (17) . Whether the average daily production numbers during healthcare system overload is below 1 is the criterion for successful suppression. The strength of NPI was quantified as the relative transmission rate calculated from ∞ / 0 . The threshold level of relative was linearly regressed on that of the log-transformed bed per 1,000 population to quantify the relative importance of the two.