layout: true background-image: url(uga.png) background-size: 120px 120px background-position: top right --- class: middle, center # COVID-19 social distancing, contact tracing, case isolation Yang Ge December - 2021 Slides link: https://yangepi.github.io/ --- # The Study Yang Ge, Zhiping Chen, Andreas Handel, Leonardo Martinez, Qian Xiao, Changwei Li, Enfu Chen, Jinren Pan, Yang Li, Feng Ling, and Ye Shen. (2021). **The impact of social distancing, contact tracing, and case isolation interventions to suppress the COVID-19 epidemic: A modeling study**. Epidemics, 36, 100483–100483. doi: https://doi.org/10.1016/j.epidem.2021.100483 --- # Backgrounds + January to February, 2020 + SARS-CoV-2 first-wave. + No vaccines. + NPIs: 1. Case isolation 1. Social distancing 1. Contact tracing --- # Motivations + Key question: Effectiveness of social distancing, contact tracing, and case isolation. + Impact: policymaking of future outbreaks control --- # SEIR Model <div class="figure" style="text-align: center"> <img src="npi1.png" alt="SEIR" width="80%" /> <p class="caption">SEIR</p> </div> --- # Social contacts `$$cnt1_{ji} - (cnt1_{ji} - cnt2_{ji})\cdot w(t)$$` `$$w(t) = \frac{1}{1 + \exp(-a(t-b))}$$` <div class="figure" style="text-align: center"> <img src="wt.png" alt="y = w(t,a,b)" width="50%" /> <p class="caption">y = w(t,a,b)</p> </div> --- # Equations `\begin{aligned} \text{ODEs} & : \\ \lambda & = \sum\limits_{j=1}^{14}\beta \cdot \Big(cnt1_{ji} - (cnt1_{ji} - cnt2_{ji})\cdot w(t)\Big) \cdot (P_j + C_j) \\ \dot S_i & = - S_i \lambda \\ \dot E_i & = S_i \lambda - E/\gamma \\ & \text{Pre-symptomatic, and then symptomatic} \\ \dot P_i & = (1-p)E/\gamma - P_i/\delta \\ \dot C_i & = P_i/\delta - C_i/\epsilon \\ & \text{Quarantine} \\ \dot Q_{pi} & = pE/\gamma - Q_{pi}/\delta \\ \dot Q_{ci} & = Q_{pi}/\delta - Q_{ci}/\theta \\ & \text{Removed} \\ \dot R_i & = C_i/\epsilon + Q_{ci}/\theta \end{aligned}` --- # Curve calibration <img src="npi2.png" width="90%" style="display: block; margin: auto;" /> --- # Scenarios predictions <img src="npi3.png" width="85%" style="display: block; margin: auto;" /> --- # Scenarios predictions <img src="npi4.png" width="85%" style="display: block; margin: auto;" /> --- # Scenarios predictions reopen + Reopen: - 90th day: 50% of base level of contact matrix strength - 180th day: 80% of base level of contact matrix strength <img src="npi5.png" width="85%" style="display: block; margin: auto;" /> --- class: middle, center # Thanks yang.ge@uga.edu https://yangepi.github.io/