Optimal Contact Tracing and Social Distancing Policies to Suppress A New Infectious Disease

Abstract

Abstract This paper studies the suppression of an infectious disease in the canonical susceptible-infectious-recovered model. It derives three results. First, if technically feasible, the optimal response to a sufficiently small outbreak is halting transmissions instead of building up immunity through infections. Second, the crucial trade-off is not between health and economic costs, but between the intensity and duration of control measures. A simple formula of observables characterises the optimum. Third, the total cost depends critically on the efficiency of contact tracing, since it allows relaxing costly social distancing without increasing transmissions. A calibration to the COVID-19 pandemic illustrates the theoretical findings.