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Table 2 Mean number of contacts stratified by study wave

From: Longitudinal social contacts among school-aged children during the COVID-19 pandemic: the Bay Area Contacts among Kids (BACK) study

  Wave 1 (May 2020) Wave 2 (September 2020) Wave 3 (February 2021)
  N = 1417
827 children, 612 households
N = 1689
982 children, 716 households
N = 1446
865 children, 639 households
  Mean (95% CI) Observations Mean (95% CI) Observations Mean (95% CI) Observations
All contacts 2.28 (1.99, 2.58) 1417 3.24 (2.93, 3.58) 1689 3.31 (3.02, 3.62) 1446
Age
 0-4 1.83 (1.26, 2.48) 135 2.39 (1.79, 3.1) 161 2.29 (1.82, 2.85) 183
 5–12 1.03 (0.77, 1.32) 445 2.53 (2.13, 2.98) 498 2.73 (2.31, 3.22) 432
 13–17 0.77 (0.53, 1.09) 236 2.1 (1.7, 2.59) 287 2.63 (2.04, 3.33) 215
 18–39 4.27 (3.43, 5.18) 265 4.49 (3.82, 5.21) 336 4.22 (3.62, 4.88) 352
 40–64 3.59 (2.9, 4.35) 328 4.23 (3.67, 4.83) 403 4.25 (3.59, 5.01) 262
 65+ 2.9 (0.4, 6) 8 1.5 (0, 6) 4 4.5 (3, 6) 2
Race
 White alone 2.25 (1.88, 2.65) 799 3.47 (3.07, 3.91) 986 3.64 (3.22, 4.09) 778
 Asian alone 2.05 (1.51, 2.66) 366 2.36 (1.96, 2.83) 391 2.55 (2.11, 3.02) 405
 Black or African American alone 2.28 (1.54, 3.14) 116 3.86 (2.48, 5.62) 103 4.1 (2.85, 5.57) 110
 Two or More Races 3.8 (1.83, 6.2) 69 4.92 (2.73, 7.8) 91 3.17 (1.74, 5.39) 58
 Some other race alone 1.85 (0.98, 2.98) 56 2.09 (1.27, 3.08) 104 3.09 (1.96, 4.49) 80
 American Indian or Alaska Native alone 2.89 (0, 21) 8 4.17 (1, 10) 6 2.29 (1, 3.67) 13
 Native Hawaiian or Pacific Islander alone 4 (1, 10) 3 2.12 (1, 3.25) 8 1 (1,1) 2
Hispanic
 Hispanic household 3.33 (2.49, 4.29) 261 3.55 (2.73, 4.56) 321 3.66 (3, 4.42) 312
 Non-Hispanic household 2.04 (1.74, 2.34) 1156 3.16 (2.83, 3.52) 1368 3.21 (2.89, 3.56) 1134
Household size
 2 2.84 (1.8, 4.08) 98 4.05 (2.54, 5.88) 123 5.14 (3.83, 6.54) 153
 3 3 (2.44, 3.63) 410 2.46 (2.06, 2.93) 443 2.89 (2.39, 3.46) 376
 4 1.81 (1.43, 2.24) 618 3.38 (2.94, 3.86) 713 2.91 (2.49, 3.36) 572
 5 or more 2.04 (1.43, 2.75) 291 3.51 (2.69, 4.55) 410 3.47 (2.89, 4.11) 345
Household income
 Less than $19,999 4.23 (2.76, 6.05) 63 3.3 (2.02, 5.14) 84 3.68 (2.5, 4.98) 85
 $20,000 to $39,999 2.65 (1.66, 3.92) 106 3.82 (2.63, 5.3) 123 3.86 (2.68, 5.34) 122
 $40,000 to $59,999 2.6 (1.54, 3.95) 110 3.35 (2.41, 4.51) 164 3.04 (2.21, 4.06) 140
 $60,000 to $79,999 3.23 (2.12, 4.59) 132 2.52 (1.86, 3.33) 173 3.25 (2.29, 4.44) 160
 $80,000 to $99,999 2.66 (1.63, 3.85) 133 3.6 (2.35, 5.3) 172 2.76 (2.08, 3.64) 172
 $100,000 to $149,999 2.59 (1.87, 3.39) 265 3.43 (2.78, 4.19) 342 3.58 (2.98, 4.24) 328
 $150,000 or more 1.5 (1.2, 1.85) 608 3.03 (2.58, 3.54) 631 3.18 (2.7, 3.69) 439
County
 San Francisco 4.81 (3.57, 6.23) 143 4.05 (3.2, 5.02) 337 3.45 (2.87, 4.08) 379
 Marin 3.62 (0, 9.67) 9 2.65 (0.72, 6.05) 24 2.69 (0.7, 6.5) 15
 Solano 2.89 (1.24, 5.08) 50 3.5 (2.3, 4.79) 76 2.72 (1.7, 3.71) 28
 Sonoma 2.84 (1.27, 5) 51 3.08 (2.11, 4.13) 93 3.19 (2, 4.52) 72
 San Mateo 2.81 (1.67, 4.21) 98 2.42 (1.78, 3.15) 162 2.36 (1.66, 3.15) 105
 Napa 2.1 (0.57, 5.33) 14 1.5 (1, 2) 6 4.85 (1.22, 10.5) 16
 Santa Clara 1.88 (1.3, 2.56) 233 3 (2.48, 3.61) 397 3.21 (2.61, 3.89) 288
 Alameda 1.8 (1.43, 2.23) 516 2.99 (2.39, 3.67) 396 3.52 (2.85, 4.29) 325
 Contra Costa 1.74 (1.23, 2.36) 303 3.47 (2.41, 4.94) 198 3.33 (2.62, 4.1) 218
Adults working from home1
 Same or less 3.67 (2.92, 4.48) 325 3.38 (2.94, 3.87) 819 3.51 (3.09, 3.96) 767
More adults working from home 1.79 (1.51, 2.09) 1037 2.96 (2.54, 3.45) 803 3.02 (2.59, 3.49) 627
Vaccination status1
 0 household members vaccinated 2.64 (2.32, 2.97) 868
1 household member vaccinated 4.32 (3.78, 4.89) 577
  1. We took 10,000 bootstrapped estimates from each wave of BACK, clustering at the household level, and computed bootstrapped mean estimates within each strata. We summarized the point estimate and 95% CI as the 2.5 and 97.5% quantiles of the distribution of bootstrapped estimates
  2. 1Does not sum to the number of individuals since this was not a required question