Table 3. Univariable Hazard Risk Ratios for ILI Among US Service Members, 18–49 Years of Age, During 2006/2007 and 2008/2009 Influenza Seasons.
| Characteristic | ILI Events | |
| No. (%) | HR (95% CI) | |
| Vaccine type | ||
| TIV | 787 (12.7) | 1.00 (Ref) |
| LAIV | 3149 (13.9) | 1.02 (0.95–1.11) |
| Recent smoking history | ||
| Yes | 1123 (14.1) | 1.09 (1.02–1.17)a |
| No | 2813 (13.4) | 1.00 (Ref) |
| Potential alcohol problem | ||
| Yes | 267 (12.0) | 0.90 (0.79–1.02) |
| No | 3669 (13.7) | 1.00 (Ref) |
| Exercise level | ||
| Minimal | 439 (14.4) | 1.05 (0.94–1.16) |
| Moderate | 2782 (13.7) | 1.00 (Ref) |
| High | 133 (10.4) | 0.79 (0.66–0.95) |
| Unknown | 582 (13.7) | 1.00 (0.91–1.09) |
| Age, y | 0.99 (0.98–0.99)a | |
| Sex | ||
| Male | 2339 (11.1) | 1.00 (Ref) |
| Female | 1597 (20.1) | 1.84 (1.72–1.96)a |
| Race/ethnicity | ||
| White | 2823 (13.4) | 1.00 (Ref) |
| Black | 486 (13.4) | 1.00 (0.91–1.10) |
| Hispanic | 290 (14.0) | 1.08 (0.95–1.22) |
| Other/unknown | 337 (15.7) | 1.17 (1.04–1.32)a |
| Marital status | ||
| Married | 2420 (13.6) | 1.00 (Ref) |
| Other | 1516 (13.7) | 1.02 (0.96–1.09) |
| Service branch | ||
| Air Force | 2363 (16.5) | 1.00 (Ref) |
| Army | 1047 (11.1) | 0.74 (0.68–0.79)a |
| Marine Corps | 197 (6.6) | 0.43 (0.37–0.50)a |
| Navy | 329 (14.6) | 0.90 (0.80–1.02) |
| Military rank | ||
| Enlisted | 3140 (14.3) | 1.00 (Ref) |
| Officer | 796 (11.4) | 0.77 (0.71–0.84)a |
| Occupation | ||
| Combat | 531 (10.2) | 0.76 (0.69–0.84)a |
| Health care | 783 (18.3) | 1.28 (1.18–1.39)a |
| Other | 2622 (13.5) | 1.00 (Ref) |
| US geographic area | ||
| Southwest | 1203 (13.8) | 1.00 (Ref) |
| Southeast | 1192 (13.3) | 0.98 (0.90–1.06) |
| Northeast | 832 (13.1) | 0.92 (0.84–1.00) |
| Northwest | 709 (14.7) | 1.04 (0.95–1.15) |
| Influenza season | ||
| 2006–2007 | 1860 (14.1) | 1.00 (Ref) |
| 2008–2009 | 2076 (13.2) | 1.07 (1.00–1.14)a |
Abbreviations: CI, confidence interval; HR, hazard ratio; ILI, influenza-like illness; LAIV, live, attenuated influenza vaccine; TIV, trivalent inactivated influenza vaccine.
a
p<0.05.