The basic reproduction number, R 0 , determines the rate of spread of a communicable disease and therefore gives fundamental information needed to plan public health interventions. Using mortality records, we estimated the rate of spread of COVID-19 among 160 counties and county-aggregates in the USA at the start of the epidemic. We show that most of the high among-county variance is explained by four factors (R 2 = 0.70): the timing of outbreak, population size, population density, and spatial location. For predictions of future spread, population density and spatial location are important, and for the latter we show that SARS-CoV-2 strains containing the G614 mutation to the spike gene are associated with higher rates of spread. Finally, the high predictability of R 0 allows extending estimates to all 3109 counties in the conterminous 48 states. The high variation of R 0 argues for public health policies enacted at the county level for controlling COVID-19. Ives and Bozzuto estimate the spread rate of COVID-19 in the USA at the start of the epidemic, extrapolating values of R 0 for 3109 counties during the period before measures were taken to reduce the spread. Most of predictive variation in county-level values of R 0 is explained by population density and spatial location, with differences among locations associated with differences among strains of SARS-CoV-2.
【저자키워드】 Infectious diseases, Evolutionary genetics, Ecological epidemiology, 【초록키워드】 COVID-19, public health, SARS-CoV-2, Mutation, Mortality, Variation, Spread, spike gene, outbreak, Public health interventions, basic reproduction number, USA, estimate, information, communicable, disease, strain, Predictive, Factor, measure, SARS-CoV-2 strain, MOST, the epidemic, spread of COVID-19, determine, explained, reduce, R 2, the timing, 【제목키워드】 USA, spread of COVID-19,