Table 2 Risk of predicted Covid-19 according to living in a community with overall social-distancing grade at various time lags.

From: Association of social distancing and face mask use with risk of COVID-19

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

  1. HR hazard ratio, CI confidence interval.
  2. Cox proportional hazards regression models were used to calculate HRs and 95% CIs.
  3. 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.
  4. bTwo-sided P values for trend were calculated using the median value of each category as a continuous variable.
  5. cModel 1 was stratified by age (<25, 25–34, 35–44, 45–54, 55–64, or ≥65), state, and calendar date at study entry.
  6. 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).
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