COVID-19 Progression Timeline and Effectiveness of Response-to-Spread Interventions across the United States

Pai Liu; Payton Beeler; Rajan K Chakrabarty

is the (which was not peer-reviewed) The copyright holder for this preprint . https://doi.org/10.1101/2020.03. 17.20037770 doi: medRxiv preprint Timing to Implement Finite Time Intervention. Previous modeling studies have shown that community level control measures are effective in reducing disease transmissibility, however, prolonged closures of schools and businesses, as well as limited public gatherings have negative socio-economic impacts that must be considered (30, 31) . The negative socio-economic impacts dictate that the community-level interventions can only last a finite amount of time. Therefore, it is of utmost importance to understand when and for how long those interventions should be put into effect, so as to maximize the net benefit. Figure 5(a) shows the output of the SEIR model under a conditional 25% reduction in transmissibility within a time window defined with an intervention start time, , and an end time, + (where represents intervention duration). Effectiveness of interventions (lasting for a variable ), which is quantified with the normalized reduction of infected population at the national epidemic peak, is plotted in Fig. 5 (a) as a function of implementation timing, which is quantified with number of weeks between and the national epidemic peak. The trends in Fig. 5 (a) show that unless the intervention could last indefinitely, a premature implementation of a finite-time intervention plan could be counterproductive. Figure 5 (b) plots the best implementation timing, * , as a function of , and a power-law relationship * ≈ 0.85 is conceived. This empirical relationship informs the optimal timing to enforce communitylevel interventions given a practically affordable intervention duration. The earliness of the statewise epidemic peaks are presented in Fig. 5 (c).