Mitigation Strategies and Compliance in the Covid-19 Fight; How Much Compliance is Enough?

Mukerjee, S.; Chow, C.; Li, M.

Today, with only 4% of the world's population, the U.S. is bearing a disproportionate share of COVID-19 infections. Seeking to understand this puzzle, we investigate how mitigation strategies and compliance can work together (or in opposition) to reduce (or increase) the spread of COVID-19 infection. Drilling down to the state level, we create specific state indices suitable for the U.S. to measure the degree of strictness of public mitigation measures. In this, we build on the Oxford Stringency Index. A modified time-varying SEIRD model, incorporating this Stringency Index as well as a Compliance Indicator to reduce the transmission, is then estimated with daily data for a sample of 6 U.S. states. These are New York, New Hampshire, New Mexico, Colorado, Texas, and Arizona. We provide a simple visual policy tool to evaluate the various combinations of mitigation policies and compliance that can reduce the basic reproduction number to less than one; this is the acknowledged threshold in the epidemiological literature to control the pandemic. States successful in combating the pandemic were able to achieve a suitable combination. Understanding of this relationship by the public and policy makers is key to controlling the pandemic. This tool has the potential to be used in a real-time, dynamic fashion for flexible policy options.