Levels of economic developement and the spread of coronavirus disease 2019 (COVID-19) in 50 U.S. states and territories and 28 European countries: an association analysis of aggregated data

The coronavirus disease 2019 (COVID-19) became a global pandemic within several months after it was first reported at the end of December, 2019. Countries in the Northern Hemisphere have been affected the most, including the United States and European countries. Contrary to the common knowledge that infectious diseases are more prevalent in low- and middle-income countries, COVID-19 appears to affect wealthy countries more. This paper attempts to quantify the relationship between COVID-19 infections and levels of economic development with data from the U.S. and Europe. Public domain data on the confirmed COVID-19 cases during January 1 and May 31, 2020 by states and territories in the U.S. and by countries in Europe were included. Incidence rate was estimated using the 2019 total population. COVID-19 cases were associated with 2019 gross domestic product (GDP) using regression models after a logarithmic transformation of the data. The U.S. data and European data were analyzed separately, considering significant heterogeneity between the two. A total of 2 451 691 COVID-19 cases during a 5-month period were analyzed, including 1 787 414 from 50 U.S. states and territories and 664 277 from 28 European countries. The overall incidence rate was 5.393/1000 for the U.S. and 1.411/1 000 for European countries with large variations. Lg (total cases) was significantly associated with lg (GDP) for U.S. states (= 1.2579, P