Table 2

Overall association of county-level Social Vulnerability Index (IRR per 10 percentile increase) with incidence and death per capita of COVID-19 as of 6 March 2021

Model 1*Model 2†Model 3‡
IRR (95% CI)P valueIRR (95% CI)P valueIRR (95% CI)P value
Incidence
Overall Social Vulnerability Index§1.03 (1.03 to 1.04)<0.0011.02 (1.02 to 1.03)<0.0011.02 (1.02 to 1.03)<0.001
Socioeconomic status1.02 (1.02 to 1.03)<0.0011.02 (1.01 to 1.02)<0.0011.02 (1.01 to 1.02)<0.001
Minority status and language1.02 (1.01 to 1.02)<0.0011.02 (1.01 to 1.02)<0.0011.02 (1.01 to 1.02)<0.001
Housing type and transport1.01 (1.00 to 1.01)0.0030.99 (0.99 to 1.00)0.070.99 (0.99 to 1.00)0.29
Household composition and disability§1.02 (1.01 to 1.02)<0.0011.01 (1.01 to 1.02)<0.0011.01 (1.01 to 1.02)<0.001
Death per capita
Overall Social Vulnerability Index§1.07 (1.06 to 1.08)<0.0011.05 (1.04 to 1.06)<0.0011.04 (1.04 to 1.05)<0.001
Socioeconomic status1.07 (1.07 to 1.08)<0.0011.05 (1.04 to 1.06)<0.0011.05 (1.04 to 1.05)<0.001
Minority status and language1.03 (1.02 to 1.03)<0.0011.01 (1.00 to 1.02)0.0031.01 (1.00 to 1.02)0.004
Housing type and transport1.06 (1.05 to 1.06)<0.0011.05 (1.04 to 1.05)<0.0011.05 (1.04 to 1.05)<0.001
Household composition and disability§1.04 (1.03 to 1.05)<0.0011.02 (1.01 to 1.02)<0.0011.02 (1.01 to 1.02)<0.001
  • *Base model: adjusted for proportion of population aged ≥65 years and state-level COVID-19 testing.

  • †Base model+CMS average HCC score (proxy for comorbidities).

  • ‡Base model+CMS average HCC score (proxy for comorbidities)+environmental factors including average daily temperature (degrees Fahrenheit), average daily precipitation and average particulate matter of diameter ≥2.5 μm.

  • §Proportion aged ≥65 years not included as a covariate for models for overall Social Vulnerability Index and household composition/disability because these indices contain the age variable.

  • CMS, Centers for Medicare and Medicaid Services; HCC, Hierarchical Condition Category; IRR, incidence rate ratio.