Table 2.
Risk of predicted Covid-19 according to living in a community with overall social-distancing grade at various time lags.
| Overall social distance gradea | Poor (F) | Fair (D) | Good (C) | Excellent (A/B) | P value for trendb |
|---|---|---|---|---|---|
| Day—0 | |||||
| No. of cases/person-time (days) | 1854/6,048,237 | 1321/3,395,812 | 1164/1,796,116 | 149/188,276 | |
| Model 1 HR (95% CI)c | 1 [Reference] | 0.92 (0.83–1.02) | 0.89 (0.78–1.01) | 0.86 (0.69–1.06) | 0.06 |
| Model 2 HR (95% CI)d | 1 [Reference] | 0.93 (0.84–1.02) | 0.89 (0.78–1.01) | 0.84 (0.68–1.05) | 0.06 |
| Day—7 | |||||
| No. of cases/person-time (days) | 1631/5,338,022 | 1373/3,533,445 | 1334/2,289,203 | 150/267,771 | |
| Model 1 HR (95% CI) | 1 [Reference] | 0.90 (0.81–1.00) | 0.86 (0.76–0.98) | 0.77 (0.62–0.96) | 0.01 |
| Model 2 HR (95% CI) | 1 [Reference] | 0.89 (0.80–0.99) | 0.85 (0.75–0.97) | 0.78 (0.63–0.97) | 0.01 |
| Day—14 | |||||
| No. of cases/person-time (days) | 1538/4,658,606 | 1457/3,688,551 | 1352/2,740,212 | 141/341,073 | |
| Model 1 HR (95% CI) | 1 [Reference] | 0.85 (0.77–0.95) | 0.79 (0.70–0.90) | 0.68 (0.54–0.84) | 1.03 × 10−4 |
| Model 2 HR (95% CI) | 1 [Reference] | 0.85 (0.77–0.95) | 0.80 (0.70–0.91) | 0.69 (0.55–0.86) | 2.61 × 10−4 |
| Day—21 | |||||
| No. of cases/person-time (days) | 1651/4,114,296 | 1441/3,851,825 | 1256/3,067,160 | 140/395,159 | |
| Model 1 HR (95% CI) | 1 [Reference] | 0.82 (0.74–0.91) | 0.74 (0.65–0.84) | 0.68 (0.55–0.85) | 3.92 × 10−6 |
| Model 2 HR (95% CI) | 1 [Reference] | 0.82 (0.74–0.91) | 0.74 (0.65–0.84) | 0.69 (0.56–0.86) | 7.03 × 10−6 |
| Day—28 | |||||
| No. of cases/person-time (days) | 1796/3,739,754 | 1389/3,995,767 | 1168/3,268,318 | 135/424,562 | |
| Model 1 HR (95% CI) | 1 [Reference] | 0.82 (0.74–0.90) | 0.75 (0.66–0.86) | 0.69 (0.55–0.86) | 1.46 × 10−6 |
| Model 2 HR (95% CI) | 1 [Reference] | 0.82 (0.74–0.91) | 0.75 (0.66–0.86) | 0.70 (0.55–0.87) | 1.94 × 10−6 |
HR hazard ratio, CI confidence interval.
Cox proportional hazards regression models were used to calculate HRs and 95% CIs.
aOverall social-distancing grades are denoted as Poor (F grade), Fair (D grade), Good (C grade), and Excellent (A + B grade). Overall social-grade categories (A, B, C, D, and F) are provided by Unacast.
bTwo-sided P values for trend were calculated using the median value of each category as a continuous variable.
cModel 1 was stratified by age (<25, 25–34, 35–44, 45–54, 55–64, or ≥65), state, and calendar date at study entry.
dModel 2 was stratified by age (<25, 25–34, 35–44, 45–54, 55–64, ≥65), state, and calendar date at study entry and further adjusted for race (White, Black, Asian, or other), sex (male or female), population density of residence (quartiles), current smoking, frontline healthcare worker, interaction with suspected or documented Covid-19, history of diabetes, heart disease, lung disease, and kidney disease (each yes or no).