3.1.1. Models Predicting Total Case Incidence
Models of key predictors of COVID-19 cases by census tract in each of the two phases are presented in Figure 1 (left points, in lighter blue). Overall, census tract characteristics consistently associated with increased risk of COVID-19 cases included higher population proportions of essential workers, those without health insurance, Black or Latinx residents, and number of LTCF beds per capita. By contrast, proportion of residents aged 20 or younger, proportion of undergraduate students, and housing density were significantly associated with decreased IRRs. Crowded housing, % aged over 80 years, and proportion of American Indian and Alaska Native (AIAN) residents were not statistically significantly associated with tract-level COVID-19 case incidence rates. All associations were statistically stable between Phase 1 and Phase 2 (i.e., there were no changes in directionality or statistical significance), but a few variables had substantive attenuations in magnitudes (i.e., more than a 10% change in point estimates toward the null): IRRs for % Black decreased from 1.20 (95% confidence interval [CI]: 1.16, 1.24) in Phase 1 to 1.04 (1.03, 1.06) in Phase 2, % Latinx decreased from 1.37 (1.30, 1.44) to 1.16 (1.13, 1.19), LTCF beds decreased from 1.39 (1.35, 1.44) to 1.06 (1.04, 1.07), and % undergraduates increased from 0.83 (0.80, 0.86) to 0.93 (0.91, 0.94).