2.3. Community-level predictors
We obtained total population counts, as well as select social, occupational, housing, and demographic data at census tract resolution from the most recent five-year (2015-2019) American Community Survey (ACS). We evaluated potential predictors hypothesized to be associated with increased risk of disease transmission, disease severity, and/or health disparities, including: population proportions of those who identify as Black or African American, Hispanic or Latino (Latinx), or American Indian or Alaska Native (AIAN); share of population with ages greater than 80 years and share with ages under 20 years; percent of population enrolled as undergraduate students or employed in essential services; the number of LTCF beds per capita; the percent of households with more than 1.5 persons per room; and housing unit density (number of housing units per square mile). We defined “essential services” following the approach of the American Civil Liberties Union (ACLU) Massachusetts. These variables are informed by and consistent with our previous modeling work at the town level, in which we used backwards model selection to select non-correlated covariates (confirming that none of the independent variables had a correlation of |r| > 0.60).