Abstract
Control of diseases transmitted from person to person may be more effectively and less economically damaging if preventive and ameliorative efforts are focused on the more vulnerable local areas rather than entire countries, provinces, or states. The spread of the COVID-19 virus is highly concentrated in urban US counties. Sixteen factors known or thought to be related to spread of the COVID-19 virus were studied by Poisson regression analysis of confirmed cases and deaths in 883 US counties with a population of 50,000 or more as of May 31, 2020. Evidence of crowding in homes, workplaces, religious gatherings, preexisting health conditions in the population, and local economic and demographic conditions, with one exception, was predictive of incidence and mortality. Based on the correlation of cases and deaths to length of stay-at-home orders, the orders were associated with about 52% reduced cases and about 55% reduced deaths from those expected without the orders.