Table 2. Odds ratios for increased serologic response against swine H1N1 influenza virus by hemagglutination inhibition assay.
| Variable | n | Swine H1N1* |
||||
|---|---|---|---|---|---|---|
| Titer >10, n (%) | Titer >20, n (%) | Bivariate OR (95% CI) | Multivariate OR (95% CI) | |||
| Age group (y) | ||||||
| <29 | 40 | 3 (7.5) | 1 (2.5) | 1.2 (0.2–6.1) | 3.5 (0.4–30.6) | |
| 29–42 | 46 | 3 (6.5) | 1 (2.2) | Reference | Reference | |
| >42 | 42 | 9 (22) | 6 (14.6) | 4.2 (1.1–16.8)† | 6.1 (0.9–41.3) | |
| Sex | ||||||
| Male | 63 | 13 (21) | 7 (11.3) | 8.4 (1.8–38.7)† | 7 (0.9–52.1) | |
| Female | 65 | 2 (3.1) | 1 (1.5) | Reference | Reference | |
| Swine exposure | ||||||
| Swine workers occasionally or never use gloves | 34 | 12 (35.3) | 7 (20.6) | 21 (4.4–100.8)† | 30.3 (3.8–243.5)† | |
| Swine workers usually or always use gloves | 14 | 1 (7.1) | 0 | 2.8 (0.2–34.2) | 2.4 (0.1–40.9) | |
| Controls not exposed to swine | 79 | 2 (2.6) | 1 (1.3) | Reference | Reference | |
| Smoked >5 packs of cigarettes in past year | ||||||
| Yes | 14 | 4 (28.6) | 3 (21.4) | 4 (1.1–14.5)† | 18.7 (2.5–141.3)† | |
| No | 114 | 11 (9.7) | 5 (4.4) | Reference | Reference | |
| Received 2002–03 influenza vaccine | ||||||
| Yes | 36 | 4 (11.4) | 1 (2.9) | 1 (0.3–3.4) | – | |
| No | 91 | 10 (11) | 7 (7.7) | Reference | – | |
| Received 2003–04 influenza vaccine | ||||||
| Yes | 43 | 6 (14.3) | 3 (7.1) | 1.6 (0.5–4.8) | 16.3 (2.5–107.4)† | |
| No | 84 | 8 (9.5) | 5 (6) | Reference | Reference | |
| Elevated titer human H1N1 (>40) | ||||||
| Positive | 39 | 2 (5.3) | 1 (2.6) | 0.3 (0.1–1.5) | – | |
| Negative | 89 | 13 (14.6) | 7 (7.9) | Reference | – | |
*OR, odds ratio; CI, confidence interval; by using proportional odds model, these titers were grouped: <10, 10, >10. †Significant odds for increased serologic response, p<0.05.