A Country-Specific COVID-19 Model

We propose a reduced-form eSIRD model to operationalize the country-specific Basic Reproduction Number and Mortality Rate for the COVID-19 pandemic. Enhanced from the classical epidemiological structural SIR model, our model has several contributions: 1) Allowing the effective Basic Reproduction Number and Mortality Rate to vary through time, directly measuring the combined effects of the pathogen progression and the population behavioral response functions; 2) Enabling interpretable comparisons with transmissibility and fatality rates normalized by population size across countries; 3) Permitting a consistent generation of probabilistic scenarios adapted to the still unfolding pandemic. We provide evidence that this stochastic model has the power to fit the empirical data and is useful for pandemic surveillance and planning purposes