Table 2. Sentinel test-negative case-control study: Participant profile by analysis period (seasonal influenza and pH1N1).
| Participant Attribute Category | Subcategory | Seasonal Influenza Analysis Period (ILI Onset: 1 November 2008 to 31 March 2009) | pH1N1 Analysis Period (ILI Onset: 17 April 2009 to 22 July 2009) | ||||
| Cases (N = 672), n/N (%) | Controls (N = 857), n/N (%) | ALL (N = 1,529), n/N(%) | Cases (N = 144), n/N (%) | Controls (N = 536), n/N (%) | ALL (N = 680), n/N(%) | ||
| 2008–09 TIV Receipt | 97 (14) | 287 (33) | 384 (25) | 45 (31) | 166 (31) | 211 (31) | |
| Age (y) | 1–8 | 100 (15) | 93 (11) | 193 (13) | 13 (9) | 41 (8) | 54 (8) |
| 9–19 | 176 (26) | 123 (14) | 299 (20) | 59 (41) | 66 (12) | 125 (18) | |
| 20–49 | 311 (46) | 384 (45) | 695 (45) | 59 (41) | 272 (51) | 331 (49) | |
| 50–64 | 69 (10) | 172 (20) | 241 (16) | 10 (7) | 109 (20) | 119 (18) | |
| ≥65 | 16 (2) | 85 (10) | 101 (7) | 3 (2) | 48 (9) | 51 (8) | |
| Median (range), y | 23 (1–85) | 38 (1–92) | 30 (1–92) | 20 (2–68) | 38 (1–92) | 33 (1–92) | |
| 2008–09 TIV immunized by age group | 1–8 | 14 (14) | 20 (22) | 34 (18) | 5 (38) | 4 (10) | 9 (17) |
| 9–19 | 14 (8) | 23 (19) | 37 (12) | 13 (22) | 6 (9) | 19 (15) | |
| 20–49 | 39 (12) | 86 (22) | 125 (18) | 22 (37) | 63 (23) | 85 (26) | |
| 50–64 | 17 (25) | 84 (49) | 101 (42) | 2 (20) | 60 (55) | 62 (52) | |
| ≥65 | 13 (81) | 74 (87) | 87 (86) | 3 (100) | 33 (69) | 36 (71) | |
| Sex | Female | 371 (55) | 503 (59) | 874 (57) | 79 (55) | 332 (62) | 411 (60) |
| Interval between ILI onset and specimen collection | ≤4 d | 569 (85) | 651 (76) | 1220 (80) | 128 (89) | 418 (78) | 546 (80) |
| 5–7 d | 103 (15) | 206 (24) | 309 (20) | 16 (11) | 118 (22) | 134 (20) | |
| Median (range) | 3 (0–7) | 3 (0–7) | 3 (0–7) | 2 (0–7) | 3 (0–7) | 3 (0–7) | |
| With chronic conditions | N | 89 (13) | 199 (23) | 288 (19) | 23 (16) | 102 (19) | 125 (18) |
| Vaccinated 2008–09 | 37 (42) | 133 (67) | 170 (59) | 14 (61) | 61 (60) | 75 (60) | |
| Without chronic conditions | N | 583 (87) | 658 (77) | 1241 (81) | 121 (84) | 434 (81) | 555 (82) |
| Vaccinated 2008–09 | 60 (10) | 154 (23) | 214 (17) | 31 (26) | 105 (24) | 136 (24) | |
| Province | Alberta | 146 (22) | 375 (44) | 521 (34) | 27 (19) | 167 (31) | 194 (29) |
| BC | 191 (28) | 189 (22) | 380 (25) | 19 (13) | 166 (31) | 185 (27) | |
| Ontario | 126 (19) | 166 (19) | 292 (19) | 34 (24) | 102 (19) | 136 (20) | |
| Quebec | 209 (31) | 127 (15) | 336 (22) | 64 (44) | 101 (19) | 165 (24) | |
| Chronic condition by province | Alberta | 19 (13) | 99 (26) | 118 (23) | 6 (22) | 34 (20) | 39 (20) |
| BC | 27 (14) | 40 (21) | 67 (18) | 6 (32) | 39 (23) | 45 (24) | |
| Ontario | 20 (16) | 33 (20) | 53 (18) | 4 (12) | 10 (10) | 14 (10) | |
| Quebec | 23 (11) | 27 (21) | 50 (15) | 7 (11) | 19 (19) | 26 (16) | |
| 2008–09 TIV immunized by province | Alberta | 15 (10) | 113 (30) | 128 (25) | 9 (33) | 56 (34) | 65 (34) |
| BC | 20 (10) | 55 (29) | 75 (20) | 4 (21) | 46 (28) | 50 (27) | |
| Ontario | 32 (25) | 75 (45) | 107 (37) | 11 (32) | 37 (36) | 48 (35) | |
| Quebec | 30 (14) | 44 (35) | 74 (22) | 21 (33) | 27 (27) | 48 (29) | |
| 2007–08 TIV immunized by province a | Alberta | 28 (20) | 121 (33) | 149 (29) | 8 (30) | 52 (33) | 52 (28) |
| Ontario | 47 (39) | 80 (51) | 127 (46) | 14 (48) | 41 (41) | 41 (32) | |
| Quebec | 33 (16) | 40 (33) | 73 (22) | 18 (31) | 28 (29) | 28 (18) | |
a
BC did not collect information on 2007–08 vaccine status. 2007–08 percentages derived based on participants for whom vaccine status known. Denominators do not include those with missing information (never exceeding four missing counts for any age category).