Table 2.
Seroprevalence of Influenza A(H7N9) Virus Antibody Titers ≥1:80 or ≥1:160, by Characteristic, Among Poultry Workers in Serological Surveys Conducted in May and December 2013
| Characteristic | First Serosurvey Positive, No. (%, 95% CI) (n = 501) |
Second Serosurvey Positive, No. (%, 95% CI) (n = 375) |
||
|---|---|---|---|---|
| ≥1:80 | ≥1:160 | ≥1:80 | ≥1:160 | |
| Age, y | ||||
| <40 | 43 (19.5, 14.5–25.4) | 11 (5.0, 2.5–8.8) | 84 (49.7, 41.9–57.5) | 23 (13.6, 8.8–19.7) |
| ≥40 | 66 (23.5, 18.7–28.9) | 25 (8.9, 5.8–12.9) | 127 (61.7, 54.6–68.3) | 33 (16.0, 11.3–21.8) |
| Sex | ||||
| Male | 61 (20.5, 16.1–25.6) | 18 (6.1, 3.6–9.4) | 110 (56.1, 48.9–63.2) | 26 (13.2, 8.9–18.9) |
| Female | 48 (23.5, 17.9–30.0) | 18 (8.8, 5.3–13.6) | 101 (56.4, 48.9–63.8) | 30 (16.8, 11.3–22.2) |
| District | ||||
| With confirmed cases | 31 (10.5, 7.3–14.6) | 6 (2.0, .8–4.4) | 161 (50.9, 45.3–56.6) | 31 (9.8, 6.5–12.1) |
| Without confirmed cases | 78 (37.7, 31.1–44.7) | 30 (14.5, 10.0–20.0) | 50 (84.7, 73.0–92.8) | 25 (42.4, 29.6–55.9) |
| With environmental swabs tested positive for H7N9 | 62 (18.0, 14.1–22.4) | 19 (5.5, 3.4–8.5) | 211 (56.3, 51.1–61.4) | 56 (14.9, 11.5–19.0) |
| Without environmental swabs tested positive for H7N9 | 47 (30.1, 23.1–38.0) | 17 (10.9, 6.0–16.9) | 0 | 0 |
| Type of market | ||||
| Retail | 81 (39.1, 32.4–46.1) | 31 (15.0, 10.4–20.6) | 211 (56.3, 51.1–61.4) | 56 (14.9, 11.5–19.0) |
| Wholesale | 28 (9.5, 6.4–13.5) | 5 (1.7, .6–3.9) | 0 | 0 |
| Duration of having job related to selling poultry, y | NA | |||
| <10 | 76 (20.3, 16.4–24.8) | 20 (5.3, 3.1–8.1) | ||
| ≥10 | 26 (26.6, 18.3–36.8) | 13 (13.4, 6.6–20.1) | ||
| Seasonal vaccination in the previous year | NA | |||
| Yes | 20 (10.1, 6.3–15.1) | 4 (2.0, .6–5.1) | ||
| No | 88 (30.2, 25.0–35.9) | 32 (11.1, 7.7–15.3) | ||
| Total | 109 (21.8, 18.2–25.6) | 36 (7.2, 5.1–9.8) | 211 (56.3, 51.1–61.4) | 56 (14.9, 11.5–19.0) |
Abbreviations: CI, confidence interval; NA, not available.