Table 1.
Demographic Characteristics of the Enrolled Participants
| Characteristic | All (n = 1992) |
ILI (n = 141) |
No ILI (n = 1851) |
P Value | |
|---|---|---|---|---|---|
| 2011–2012 | |||||
| Male sex | 992 (49.8) | 61 (43.3) | 933 (50.4) | NSa | |
| Age, y, mean (range) | 69.6 (60–93) | 68.8 (60–89) | 69.6 (60–93) | NSb | |
| Influenza vaccination 2011–2012 | 1512 (75.9) | 115 (81.6) | 1396 (75.4) | NSa | |
| Multiple ILIs |
|||||
| 2 | 2 (1.4) | ||||
| Asymptomatic controlsc (n = 340) |
All (n = 2368) |
ILI (n = 260) |
No ILI (n = 2108) |
P Value | |
| 2012–2013 | |||||
| Male sex | 155 (45.6) | 1177 (49.7) | 119 (45.8) | 1058 (50.2) | NSa |
| Age, y, mean (range) | 73.8 (61–93) | 70.7 (60–95) | 70.1 (60–89) | 70.7 (60–95) | NSb |
| Influenza vaccination 2012–2013 | 261 (76.8) | 1622 (68.5) | 175 (67.3) | 1448 (68.7) | NSa |
| Multiple ILIs | |||||
| 2 | 14 (5.4) | ||||
| 3 | 2 (0.8) | ||||
Data are presented as No. (%) unless otherwise indicated.
Abbreviations: ILI, influenza-like illness; NS, not significant.
aPearson χ2 test.
bIndependent samples t test of the means.
cIndividuals in the asymptomatic subset were selected to be evenly distributed over the different age groups; therefore, the overall vaccination level was higher in the asymptomatic subset compared to the ILI and non-ILI groups.