Table 3:
Crude associations of COVID-19 risk factors with seroincidence, May 2020-January 2021
| No. of seronegative participants in Period 1 * | No. of incident infections in Period 2 ** | Total person- years of follow up | Incidence rate per 100 person-years (95% CI) | Rate Ratio (95% CI) | |
|---|---|---|---|---|---|
| Total | 3,422 | 161 | 1,646.04 | 9.8 (8.3, 11.5) | |
| Household factors | |||||
| Household crowding | 822 | 43 | 378.88 | 11.4 (8.3, 15.4) | 1.21 (0.85, 1.71) |
| No household crowding | 2,600 | 118 | 1,267.16 | 9.3 (7.7, 11.2) | ref |
| Child in household | 653 | 28 | 296.07 | 9.5 (6.5, 13.8) | 0.95 (0.62, 1.42) |
| No child in household | 2,769 | 133 | 1,349.97 | 9.9 (8.3, 11.7) | ref |
| Confirmed case in household member | 23 | 12 | 102.28^ | 11.7 (5.2, 26.6) | 15.7 (8.71, 28.27) |
| No confirmed case in household member | 3,399 | 149 | 19,938.30^ | 0.7 (0.6, 0.9) | ref |
| Social distancing | |||||
| Social distancing with people you know | |||||
| Always | 2,616 | 113 | 1,258.00 | 8.9 (7.4, 10.7) | 0.29 (0.14, 0.69) |
| Sometimes | 660 | 34 | 319.00 | 10.6 (7.6, 14.7) | 0.35 (0.16, 0.86) |
| Never | 53 | 7 | 23.30 | 30.0 (13.8, 52.4) | ref |
| Not Applicable | 53 | 4 | 24.50 | 16.3 (5.3, 37.5) | 0.53 (0.13, 1.83) |
| Social distancing with people you do not know | |||||
| Always | 1,137 | 51 | 543.00 | 9.4 (7.1, 12.2) | 0.54 (0.33, 0.89) |
| Sometimes | 1,787 | 79 | 868.00 | 9.1 (7.3, 11.3) | 0.52 (0.33, 0.84) |
| Never | 300 | 24 | 139.00 | 17.3 (11.5, 24.8) | ref |
| Not Applicable | 158 | 4 | 74.50 | 5.4 (1.7, 13.9) | 0.31 (0.09, 0.83) |
| Spent time in public places | |||||
| Attended mass gathering(s) | 350 | 18 | 174.89 | 10.3 (6.4, 16.5) | 1.05 (0.63, 1.69) |
| Did not attend mass gathering(s) | 3,072 | 143 | 1,471.15 | 9.7 (8.2, 11.5) | ref |
| Indoor dining/bar | 1,755 | 108 | 843.86 | 12.8 (10.5, 15.5) | 1.93 (1.39, 2.70) |
| No indoor dining/bar | 1,667 | 53 | 802.18 | 6.6 (5.0, 8.7) | ref |
| Outdoor dining/bar | 1,869 | 97 | 924.35 | 10.5 (8.6, 12.9) | 1.18 (0.63, 1.62) |
| No outdoor dining/bar | 1,553 | 64 | 721.70 | 8.9 (6.9, 11.4) | ref |
| Visited place of worship | 359 | 29 | 168.87 | 17.2 (11.7, 25.1) | 1.92 (1.26, 2.84) |
| Did not visit place of worship | 3,063 | 132 | 1,477.17 | 8.9 (7.5, 10.6) | ref |
| Visited public park/public pool | 2,189 | 100 | 1,076.41 | 9.3 (7.6, 11.4) | 0.86 (0.63, 1.19) |
| Did not visit public park/pool | 1,233 | 61 | 569.63 | 10.7 (8.3, 13.9) | ref |
| Gathered in groups ≥ 10 | |||||
| No | 126 | 6 | 63.11 | 9.5 (4.2, 21.6) | ref |
| Indoors only | 231 | 11 | 109.34 | 10.1 (5.5, 18.4) | 1.06 (0.39,3.09) |
| Outdoors only | 647 | 38 | 318.32 | 11.9 (8.6, 16.6) | 1.26 (0.55, 3.26) |
| Indoors and outdoors | 2,418 | 106 | 1,155.28 | 9.2 (7.6, 11.1) | 0.96 (0.45, 2.42) |
| Mask Use | |||||
| Mask while grocery shopping | |||||
| Did not go grocery shopping | 133 | 6 | 63.43 | 9.5 (4.2, 21.5) | ref |
| Always | 3,084 | 140 | 1,489.12 | 9.4 (7.9, 11.1) | 0.99 (0.46, 2.99) |
| Sometimes | 132 | 12 | 57.22 | 21.0 (11.6, 38.0) | 10.57 (4.00, 30.51) |
| Never | 33 | 0 | 15.11 | 0 | 0 (0, 2.71) |
| Mask while indoors visiting non-household members | |||||
| N/A (Did no visit non-household members indoors) | 669 | 19 | 319.92 | 5.9 (3.8, 9.4) | ref |
| Always | 1,118 | 43 | 546.26 | 7.9 (5.8, 10.7) | 1.32 (0.77, 2.32) |
| Sometimes | 1,131 | 63 | 546.44 | 11.5 (8.9, 14.9) | 1.94 (1.37, 3.31) |
| Never | 463 | 33 | 211.58 | 15.6 (10.9, 22.22) | 2.62 (1.5, 4.7) |
| Mask while indoors at work | |||||
| N/A (Did not attend indoor workplace) | 1,642 | 63 | 789.46 | 8.0 (6.2, 10.3) | ref |
| Always | 1,372 | 71 | 660.60 | 10.7 (8.5, 13.6) | 1.34 (0.95, 1.89) |
| Sometimes | 299 | 18 | 144.08 | 12.5 (7.8, 20.1) | 1.56 (0.90, 2.60) |
| Never | 68 | 6 | 30.05 | 20.0 (8.6, 46.2) | 2.50 (0.98, 5.26) |
| Mask while at salon/gym | |||||
| N/A (Did not attend salon/gym) | 1,567 | 56 | 749.79 | 7.5 (5.7, 9.8) | ref |
| Always | 1,527 | 75 | 743.45 | 10.1 (8.0, 12.7) | 1.31 (0.95, 1.91) |
| Sometimes | 180 | 20 | 82.69 | 24.2 (15.2, 38.5) | 3.23 (1.90, 5.23) |
| Never | 108 | 7 | 48.94 | 14.3 (6.6, 30.8) | 1.91 (0.80, 4.01) |
| Outdoor mask use | |||||
| Mask use outdoors | 1,562 | 67 | 753.27 | 8.9 (7.0, 11.4) | 0.84 (0.67, 1.15) |
| No mask use outdoors | 1,860 | 94 | 892.78 | 10.5 (8.6, 13.0) | ref |
| Movement during the pandemic | |||||
| Use of public transit | |||||
| Avoided or did not use | 2,975 | 138 | 1,434.70 | 9.6 (8.1, 11.4) | 0.88 (0.57, 1.40) |
| Used public transit | 447 | 23 | 211.35 | 10.9 (7.2, 16.6) | ref |
| Recent air travel (August - November 2020) | |||||
| Yes | 582 | 39 | 287.91 | 13.5 (9.8, 18.7) | 1.52 (1.05, 2.17) |
| No | 2,800 | 119 | 1,336.97 | 8.9 (7.4, 10.7) | ref |
| Missing | 40 | 3 | 21.17 | 14.2 (4.4, 46.0) | -- |
| Other potential risk factors | |||||
| Alcohol use *** | 523 | 37 | 249.28 | 14.8 (10.6, 20.7) | 1.67 (1.14, 2.39) |
| Substance use **** | 914 | 45 | 443.40 | 10.1 (7.5, 13.7) | 1.05 (0.73, 1.47) |
| Any comorbidities ^^ | 1,490 | 69 | 714.52 | 9.7 (7.6, 12.3) | 0.97 (0.71, 1.33) |
| Changes in county-level community transmission | |||||
| High (0.327–3.30) | 1,139 | 76 | 536.00 | 14.2 (11.4, 17.5) | ref |
| Medium (0.211–0.327) | 1,140 | 37 | 557.00 | 6.6 (4.8, 9.1) | 0.46 (0.31, 0.69) |
| Low (0–0.211) | 1,139 | 48 | 550.00 | 8.7 (6.5, 11.4) | 0.61 (0.42, 0.88) |
| Missing | 4 | -- | 1.00 | ||
*
May - September 2020
**
November 2020 - January 2021
***
Having more than 6 alcoholic drinks on one occasion in last month
****
Used prescription opioids, street opioids, or cannabis in last month
^
Person-time is in person-months
^^
>60 years old, or reported co-morbidity, or current smoker. Comorbidity was defined as having history of heart attack, depression, angina, immunosuppression, type 2 diabetes, high blood pressure, cancer, asthma, COPD, chronic kidney disease, and/or HIV/AIDS