TABLE 1.
Distribution of sociodemographic and risk factor characteristics according to eligibility criterion change
| n | Group A*, n (%) | Group B†, n (%) | Group C‡, n (%) | |
|---|---|---|---|---|
| Total | 458 | 174 (38.0) | 206 (45.0) | 78 (17.0) |
| Female | 211 | 88 (50.6) | 87 (42.2) | 36 (46.2) |
| Ethnicity | ||||
| Aboriginal | 296 | 99 (56.9) | 142 (68.9) | 55 (70.5) |
| Caucasian | 127 | 58 (33.3) | 50 (24.3) | 19 (24.4) |
| Other | 35 | 17 (9.8) | 14 (6.8) | 4 (5.1) |
| Age, years | ||||
| 18–29 | 120 | 41 (23.6) | 66 (32.0) | 13 (16.7) |
| 30–39 | 97 | 52 (29.9) | 30 (14.6) | 15 (19.2) |
| 40–49 | 147 | 56 (32.2) | 60 (29.1) | 31 (39.7) |
| 50+ | 94 | 25 (14.4) | 50 (24.3) | 19 (24.4) |
| High school graduate | ||||
| Yes | 191 | 81 (46.6) | 81 (39.3) | 29 (37.2) |
| No | 236 | 84 (48.3) | 113 (54.9) | 39 (50.0) |
| Unknown | 31 | 9 (5.2) | 12 (5.8) | 10 (12.8) |
| Employed | ||||
| No | 342 | 122 (70.1) | 155 (75.2) | 65 (83.3) |
| Yes | 111 | 50 (28.7) | 48 (23.3) | 13 (16.7) |
| Unknown | 5 | 2 (1.1) | 3 (1.5) | 0 (0.0) |
| Annual household income | ||||
| <$10,000 | 126 | 44 (25.3) | 62 (30.1) | 20 (25.6) |
| $10,000–29,999 | 51 | 32 (18.4) | 15 (7.3) | 4 (5.1) |
| ≥$30,000 | 242 | 81 (46.6) | 113 (54.9) | 48 (61.5) |
| Unknown | 39 | 17 (9.8) | 16 (7.8) | 6 (7.7) |
| Location of residence | ||||
| Inner city | 290 | 106 (60.9) | 133 (64.6) | 51 (65.4) |
| Suburb/rural | 91 | 40 (23.0) | 42 (20.4) | 9 (11.5) |
| Unknown | 77 | 28 (16.1) | 31 (15.0) | 18 (23.1) |
| Had influenza-like illness within one month of enrollment | ||||
| No | 380 | 138 (79.3) | 175 (85.0) | 67 (85.9) |
| Yes | 58 | 28 (16.1) | 23 (11.2) | 7 (9.0) |
| Unknown | 20 | 8 (4.6) | 8 (3.9) | 4 (5.1) |
| Body mass index | ||||
| Underweight/normal | 277 | 108 (62.1) | 120 (58.3) | 49 (62.8) |
| Overweight/obese | 181 | 66 (37.9) | 86 (41.7) | 29 (37.2) |
| Pregnant | 25 | 12 (6.9) | 11 (5.3) | 2 (2.6) |
| Chronic heart disease | 15 | 7 (4.0) | 5 (2.4) | 3 (3.8) |
| Diabetes | 49 | 23 (13.2) | 15 (7.3) | 11 (14.1) |
| Lung disease | 100 | 47 (27.0) | 33 (16.0) | 20 (25.6) |
| Immunocompromised§ | 65 | 35 (20.1) | 13 (6.3) | 17 (21.8) |
| HIV | 57 | 32 (18.4) | 12 (5.8) | 13 (16.7) |
| Smoker | 317 | 121 (69.5) | 147 (71.4) | 49 (62.8) |
*
Enrolled before November 13, 2009;
†
Enrolled on or after November 13, 2009; did not receive pH1N1 vaccine;
‡
Enrolled on or after November 13, 2009; received pH1N1 vaccine;
§
Participants were coded as immunocompromised if they had any of the following conditions: cancer, HIV, chemotherapy or steroid treatment