Fig 3 -

Relationships through time between either COVID-19 case (blue) or death (red) rates and proportion of U.S. county populations comprised of foreign-born non-citizens (A), females (B), and residents living in rural settings (C), as well as the county population density (D). Partial slopes through time represent the strength of relationship for each variable. Error bars for each month are 95% confidence intervals. Filled circles are significantly different from zero, and open circles are not. Dashed lines indicate the approximate time when the alpha (α), delta (δ), and omicron (o) variants of SARS-CoV-2 started to spread in the U.S. Dot-dashed lines indicate when vaccination (Vax) and boosting (Boost) became widespread in the U.S.