Table 1. Characteristics of samples from influenza-like illness patients eligible for vaccine effectiveness analysis, Israel, influenza season 2014/15 (n = 1,005).
| Characteristics | Controls (n = 698) | Influenza types and subtypes of cases (n = 307) | Total (n = 1,005) | p valuec | ||||
|---|---|---|---|---|---|---|---|---|
| Total A (n = 277) | A(H1N1)pdm09 (n = 17) | A(H3N2) (n = 257) | A(unsubtyped) (n = 3) | B (n = 30) | ||||
| n (%)a | n (%)a | n (%)a | n (%)a | n (%)a | n (%)a | n (%)b | ||
| Age groups | ||||||||
| 6 months–17 years | 413 (70.2) | 165 (28.1) | 7 (1.2) | 157 (26.7) | 1 (0.2) | 10 (1.7) | 588 (58.5) | 0.83 |
| 18–44 years | 193 (68.0) | 76 (26.8) | 7 (2.5) | 68 (23.9) | 1 (0.4) | 15 (5.3) | 284 (28.2) | |
| 45–64 years | 59 (66.3) | 27 (30.3) | 2 (2.2) | 24 (27.0) | 1 (1.1) | 3 (3.4) | 89 (8.9) | |
| ≥ 65 years | 33 (75.0) | 9 (20.5) | 1 (2.3) | 8 (18.2) | 0 (0) | 2 (4.5) | 44 (4.4) | |
| Sex | ||||||||
| Male | 360 (69.4) | 142 (27.3) | 8 (1.5) | 133 (25.6) | 1 (0.2) | 17 (3.3) | 519 (51.6) | 0.95 |
| Female | 338 (69.6) | 135 (27.8) | 9 (1.8) | 124 (25.5) | 2 (0.4) | 13 (2.7) | 486 (48.4) | |
| Interval between symptom onset and swab | ||||||||
| 0–1 days | 365 (71.0) | 134 (26.1) | 7 (1.4) | 126 (24.5) | 1 (0.2) | 15 (2.9) | 514 (51.1) | 0.53 |
| 2–4 days | 299 (67.0) | 133 (29.8) | 9 (2.0) | 122 (27.3) | 2 (0.4) | 14 (3.1) | 446 (44.4) | |
| 5–7 days | 34 (75.6) | 10 (22.2) | 1 (2.2) | 9 (20) | 0 (0) | 1 (2.2) | 45 (4.5) | |
| Vaccination statusd | ||||||||
| Unvaccinated | 577 (69.9) | 222 (26.9) | 15 (1.8) | 204 (24.7) | 3 (0.4) | 26 (3.1) | 825 (82.0) | 0.47 |
| Vaccinated (TIV) | 121 (67.2) | 55 (30.6) | 2 (1.1) | 53 (29.4) | 0 (0) | 4 (2.2) | 180 (17.9) | |
TIV: trivalent inactivated vaccine.
a Percentage based on total of each row.
b Percentage based on the total of 1,005.
c Analysis performed for influenza positive (cases) vs negative (controls).
d Individuals receiving live attenuated influenza vaccine (LAIV) (n=10) were excluded from the table and analysis.