We denote the proportion of the population that were recorded as being hospitalized or as having died on day t as h(t) and d(t), respectively; these are known from the data. We denote the proportion susceptible as s(t), and the per capita incidence on day t as i(t). We do not assume that infectives were necessarily symptomatic, but they are all assumed to have become immune. Our model assumes that mixing within the population can be approximated as homogeneous. We assume a form for the effective reproduction number that incorporates the build-up of immunity in the population and social distancing,