Population density and basic reproductive number of COVID-19 across United States counties

• DOI: 10.1371/journal.pone.0249271
• Publication Date: 2021-04-21T22:24:55Z
• Authors: Karla Therese L. Sy; Laura F. White; Brooke E. Nichols
• Keywords: 2019-20 coronavirus outbreak; Pandemic; Population density

The basic reproductive number (R0) is a function of contact rates among individuals, transmission probability, and duration infectiousness. We sought to determine the association between population density R0 SARS-CoV-2 across U.S. counties. conducted cross-sectional analysis using linear mixed models with random intercept fixed slopes assess R0, controlled for state-level effects intercepts. also assessed whether was differential county-level main mode transportation percentage as proxy accessibility, adjusted median household income. United States counties 1.66 (IQR: 1.35-2.11). A threshold 22 people/km2 needed sustain an outbreak. Counties greater have SARS-CoV-2, likely due increased in areas density. An increase one unit log by 0.16 (95% CI: 0.13 0.19). This remained when effect on not modified mode. Our findings suggest that dense necessary disease transmission. estimates need consider this geographic variability proper planning resource allocation, particularly epidemics newly emerge old outbreaks resurge.