Background
Methods
Study design and population
Instrument and data collection
Informed consent
Statistical analysis
Results
Total (N = 1137) | Non-infected (N = 1113) | Infected (N = 24) | P value | |
---|---|---|---|---|
Sex (Male%) | 505/1137 (44.42%) | 492/1113 (44.2%) | 13/24 (54.17%) | 0.331 |
Age (mean ± SD) | 28.85 ± 13.23 | 28.8 ± 13.2 | 29.8 ± 13.1 | 0.712 |
15–19 | 215/1137 (18.91%) | 209/1113 (18.78%) | 6/24 (25%) | 0.441 |
20–44 | 745/1137 (65.52%) | 734/1113 (65.95%) | 11/24 (45.83%) | 0.040 |
45–54 | 94/1137 (8.27%) | 91/1113 (8.18%) | 3/24 (12.5%) | 0.442 |
55–64 | 54/1137 (4.75%) | 53/1113 (4.76%) | 1/24 (4.17%) | 1.000 |
65–74 | 23/1137 (2.02%) | 23/1113 (2.07%) | 0/24 (0%) | 1.000 |
75–84 | 3/1137 (0.26%) | 3/1113 (0.27%) | 0/24 (0%) | 1.000 |
Education level (%) | ||||
Primary education | 70/1137 (6.16%) | 67/1113 (6.02%) | 3/24 (12.5%) | 0.180 |
Secondary education | 631/1137 (55.5%) | 620/1113 (55.71%) | 11/24 (45.83%) | 0.336 |
Bachelor’s degree | 335/1137 (29.46%) | 328/1113 (29.47%) | 7/24 (29.17%) | 0.974 |
Master’s degree or above | 101/1137 (8.88%) | 98/1113 (8.81%) | 3/24 (12.5%) | 0.465 |
Chronic diseases (%) | ||||
Hypertension | 38/1137 (3.34%) | 37/1113 (3.32%) | 1/24 (4.17%) | 0.561 |
Diabetes mellitus | 13/1137 (1.14%) | 13/1113 (1.17%) | 0/24 (0%) | 1.000 |
Dyslipidaemia | 10/1137 (0.88%) | 10/1113 (0.9%) | 0/24 (0%) | 1.000 |
Gout/hyperuricaemia | 7/1137 (0.62%) | 7/1113 (0.63%) | 0/24 (0%) | 1.000 |
Coronary artery disease | 6/1137 (0.53%) | 6/1113 (0.54%) | 0/24 (0%) | 1.000 |
Hepatitis | 6/1137 (0.53%) | 5/1113 (0.45%) | 1/24 (4.17%) | 0.120 |
Other | 36/1137 (3.17%) | 35/1113 (3.14%) | 1/24 (4.17%) | 0.542 |
Current smoker (%) | 132/1137 (11.61%) | 130/1113 (11.68%) | 2/24 (8.33%) | 1.000 |
Ex-smoker (%) | 87/1137 (7.65%) | 84/1113 (7.55%) | 3/24 (12.5%) | 0.422 |
Never-smoker (%) | 918/1137 (80.74%) | 899/1113 (80.77%) | 19/24 (79.17%) | 0.844 |
Alcohol consumption (%) | 37/1137 (3.25%) | 36/1113 (3.23%) | 1/24 (4.17%) | 0.552 |
Personal protective health behaviour and measures for COVID-19 in the local community in which the participants stayed before returning to Macao
Total (N = 1137) | Non-infected (N = 1113) | Infected (N = 24) | P value | |
---|---|---|---|---|
Within 14 days before returned to Macao | ||||
COVID-19 was spreading in the country in which you stayed (Yes, %) | 902/1137 (79.33%) | 884/1113 (79.42%) | 18/24 (75%) | 0.596 |
Underwent mandatory self-quarantine at home (Yes, %) | 488/1137 (42.92%) | 477/1113 (42.86%) | 11/24 (45.83%) | 0.771 |
Had traffic restrictions in the country in which you stayed (Yes, %) | 375/1137 (32.98%) | 370/1113 (33.24%) | 5/24 (20.83%) | 0.201 |
Provided COVID-19 testing for every symptomatic people in the country in which you stayed (Yes, %) | 642/1137 (56.46%) | 632/1113 (56.78%) | 10/24 (41.67%) | 0.139 |
Public entertainment venues were shut down in the country in which you stayed (Yes, %) | 557/1137 (48.99%) | 548/1113 (49.24%) | 9/24 (37.5%) | 0.255 |
Contact history and frequency of outdoor activities
Total (N = 1137) | Non-infected (N = 1113) | Infected (N = 24) | P value | |
---|---|---|---|---|
Contact history | ||||
Went to any hospitals or clinics for any reason (Yes, %) | 56/1137 (4.93%) | 53/1113 (4.76%) | 3/24 (12.5%) | 0.110 |
Went to hospitals or clinics for respiratory symptoms (Yes, %) | 20/1137 (1.76%) | 18/1113 (1.62%) | 2/24 (8.33%) | 0.064 |
Had physical contact with anyone who had respiratory symptoms (Yes, %) | 91/1137 (8%) | 85/1113 (7.64%) | 6/24 (25%) | 0.002 |
If yes, did you wear a mask during your contact (Yes, %) | 58/91 (63.74%) | 57/85 (67.06%) | 1/6 (16.67%) | 0.022 |
If yes, did you wash your hands after your contact (Yes, %) | 84/91 (92.31%) | 81/85 (95.29%) | 3/6 (50%) | 0.005 |
Had physical contact with suspected/confirmed COVID-19 patients (including family members) (Yes, %) | 25/1137 (2.2%) | 21/1113 (1.89%) | 4/24 (16.67%) | 0.001 |
If yes, did you wear a mask during the contact (Yes, %) | 13/25 (52%) | 13/21 (61.9%) | 0/4 (0%) | 0.039 |
If yes, did you wash your hands after your contact (Yes, %) | 25/1137 (2.2%) | 20/21 (95.24%) | 2/4 (50%) | 0.057 |
Frequency of outdoor activities (Total number measured in a 14-day interval before returning to Macau) | ||||
Went to workplace (mean ± std. deviation) | 0.73 ± 2.41 | 0.7 ± 2.4 | 0.8 ± 2.6 | 0.833 |
Went to school (mean ± std. deviation) | 2.32 ± 3.7 | 2.3 ± 3.7 | 3.4 ± 5.1 | 0.291 |
Went to crowded places, such as supermarkets, malls, and cinemas (mean ± std. deviation) | 2.34 ± 2.43 | 2.3 ± 2.4 | 3.8 ± 4.6 | 0.142 |
Took public transportation vehicles, such as bus, underground transit, train, and aircraft but excluding taxi (mean ± std. deviation) | 2.52 ± 4.36 | 2.5 ± 4.3 | 4.5 ± 5.7 | 0.110 |
Participated in high-risk gathering activities defined by interacting with people within 2 m without wearing a mask such as parties, bars, restaurants, family and friend gatherings (mean ± std. deviation) | 0.82 ± 2.77 | 0.7 ± 2.3 | 5.4 ± 10.1 | 0.034 |
Mask usage behaviour, timing and duration for handwashing
Total (N = 1137) | Non-infected (N = 1113) | Infected (N = 24) | P value | |
---|---|---|---|---|
Within 14 days before you returned to Macao, did you wear a mask when outdoors? | ||||
Each time (%) | 713/1137 (62.71%) | 707/1113 (63.52%) | 6/24 (25%) | < 0.001 |
Sometimes (%) | 248/1137 (21.81%) | 242/1113 (21.74%) | 6/24 (25%) | 0.702 |
Seldom (%) | 91/1137 (8%) | 88/1113 (7.91%) | 3/24 (12.5%) | 0.412 |
Never (%) | 84/1137 (7.39%) | 76/1113 (6.83%) | 8/24 (33.33%) | < 0.001 |
Your opinion on the frequency of accidentally touching the mouth and nose area after wearing a mask | ||||
Less (%) | 906/1134 (79.89%) | 888/1113 (79.78%) | 18/21 (85.71%) | 0.783 |
Same (%) | 178/1134 (15.7%) | 177/1113 (15.9%) | 1/21 (4.76%) | 0.230 |
Increase (%) | 50/1134 (4.41%) | 48/1113 (4.31%) | 2/21 (9.52%) | 0.236 |
Do you think that hand hygiene is less important after wearing a mask? (yes, %) | 56/1134 (4.94%) | 55/1113 (4.94%) | 1/21 (4.76%) | 1.000 |
Did you frequently wash hands under the following situations within 14 days before returning to Macao? | ||||
When your hands are visibly dirty (Yes, %) | 906/1137 (79.68%) | 885/1113 (79.51%) | 21/24 (87.5%) | 0.447 |
Before eating (Yes, %) | 832/1137 (73.18%) | 818/1113 (73.5%) | 14/24 (58.33%) | 0.087 |
Before handling food or cooking (Yes, %) | 1041/1137 (91.56%) | 1020/1113 (91.64%) | 21/24 (87.5%) | 0.448 |
After handling food or cooking (Yes, %) | 1066/1137 (93.76%) | 1048/1113 (94.16%) | 18/24 (75%) | < 0.001 |
After defecation (Yes, %) | 1084/1137 (95.34%) | 1063/1113 (95.51%) | 21/24 (87.5%) | 0.097 |
After a toilet trip (Yes, %) | 1037/1137 (91.2%) | 1018/1113 (91.46%) | 19/24 (79.17%) | 0.035 |
After outdoor activity (Yes, %) | 1127/1137 (99.12%) | 1107/1113 (99.46%) | 20/24 (83.33%) | < 0.001 |
Before attending to a child or sick person (Yes, %) | 1048/1137 (92.17%) | 1028/1113 (92.36%) | 20/24 (83.33%) | 0.112 |
After attending to a child or sick person (Yes, %) | 1047/1137 (92.08%) | 1027/1113 (92.27%) | 20/24 (83.33%) | 0.115 |
After sneezing or coughing (Yes, %) | 909/1137 (79.95%) | 896/1113 (80.5%) | 13/24 (54.17%) | 0.001 |
After handling pet (Yes, %) | 918/1137 (80.74%) | 904/1113 (81.22%) | 14/24 (58.33%) | 0.005 |
Before touching the mouth and nose area (Yes, %) | 975/1137 (85.75%) | 963/1113 (86.52%) | 12/24 (50%) | < 0.001 |
Duration for handwashing each time within 14 days before returning to Macao (seconds, mean ± std. deviation) | 23.6 ± 16.1 | 23.7 ± 16.1 | 18.8 ± 11.2 | 0.136 |
Handwashing for over 20 s each time (yes, %) | 356/1127 (31.59%) | 352/1103 (31.91%) | 4/24 (16.67%) | 0.125 |
The estimated number of handwashes with soap or alcoholic sanitizers per day within 14 days before returning to Macao (mean ± std. deviation) | 9.2 ± 8.4 | 9.2 ± 8.4 | 9.1 ± 8.4 | 0.958 |
Risk and protective factors associated with COVID-19 infection
Crude Odds Ratio (95% CI) | Adjusted Odds Ratioa (95% CI) | |
---|---|---|
Age | 1.005 (0.977, 1.035) | |
Male | 1.492 (0.663, 3.359) | |
Hypertension | 1.163 (0.153, 8.817) | |
Had physical contact with anyone who had respiratory symptoms | 10.4 (3.270, 33.079)*** | |
Had physical contact with suspected/confirmed COVID-19 patients | 12.381 (4.261, 35.973)*** | 12.108 (3.380, 43.376)*** |
Wearing a mask whenever outdoors | 0.191 (0.075, 0.486)*** | 0.307 (0.109, 0.867)* |
Participated in high-risk gathering activities (interacted with people within 2 m without wearing a mask) | 1.155 (1.089, 1.225)*** | 1.129 (1.048, 1.216)*** |
Wash hands after handling food or cooking | 0.186 (0.071, 0.485)*** | |
Wash hands after a toilet trip | 0.355 (0.130, 0.971)* | |
Wash hands after outdoor activity | 0.027 (0.007, 0.104)*** | 0.021 (0.003, 0.134)*** |
Wash hands after sneezing or coughing | 0.286 (0.127, 0.648)*** | |
Wash hands after handling pets | 0.324 (0.142, 0.739)** | |
Wash hands before touching the mouth and nose area | 0.156 (0.069, 0.353)*** | 0.303 (0.114, 0.808)* |
Handwashing for over 20 s each time | 0.427 (0.145, 1.258) |