STUDY: The impact of characteristics of US counties on COVID-19 incidence

Understanding the epidemiology of SARS-CoV-2 is essential for public health control efforts. Social, demographic, and political characteristics at the US county level might be associated with changes in SARS-CoV-2 case incidence.

We conducted a retrospective analysis of the relationship between the change in reported SARS-CoV-2 case counts at the US county level during June 1, 2020 – June 30,2020 and social, demographic, and political characteristics of the county.

1023/3142 US counties were included in the analysis. 678 (66·3%) had increasing, and 345 (33·7%) had non-increasing SARS-CoV-2 case counts between June 1 – June 30, 2020. In bivariate analysis, counties with increasing case counts had significantly higher Social Deprivation Index (median 48, IQR 24 – 72) than counties with non-increasing case counts (median 40, IQR 19 – 66; p=0·009). Counties with increasing case counts were significantly more likely to be metropolitan areas of 250,000 – 1 million population (p&0·001), to have a higher percentage of Black residents (9% vs. 6%, p=0·013), and to have voted for the Republican presidential candidate in 2016 by a 10-point or greater margin (p=0·044). In the multivariable model, metropolitan areas of 250,000 – 1 million population, higher percentage of Black residents and a 10-point or greater Republican victory were independently associated with increasing case counts.

Increasing case counts of SARS-CoV-2 in the US during June 2020 were associated with a combination of sociodemographic and political factors. Addressing social disadvantage and differential belief systems that may correspond with political alignment will play a critical role in pandemic control.