Volume 17, Number 8—August 2011
CME ACTIVITY
Risk Factors for Pandemic (H1N1) 2009 Seroconversion among Adults, Singapore, 2009
Wei-Yen Lim
, Cynthia H.J. Chen, Yi Ma, Mark I.C. Chen, Vernon J.M. Lee, Alex R. Cook, Linda W.L. Tan, Norberto Flores Tabo, Ian G. Barr, Lin Cui, Raymond T.P. Lin, Yee Sin Leo, and Kee Seng Chia
, Cynthia H.J. Chen, Yi Ma, Mark I.C. Chen, Vernon J.M. Lee, Alex R. Cook, Linda W.L. Tan, Norberto Flores Tabo, Ian G. Barr, Lin Cui, Raymond T.P. Lin, Yee Sin Leo, and Kee Seng ChiaTable
Comparison of participants who provided follow-up blood samples with cohort at start of study of risk factors for pandemic (H1N1) 2009 seroconversion, Singapore, 2009*
| Characteristic | Total, n = 828 | Respondents, n = 727 |
|---|---|---|
| Age, y, mean (SD) |
43.4 (12.0) |
43.6 (11.8) |
| Age group, y | ||
| 20–29 | 149 (18.0) | 124 (17.1) |
| 30–39 | 131 (15.8) | 113 (15.5) |
| 40–49 | 285 (34.4) | 260 (35.8) |
| 50–59 | 175 (21.1) | 155 (21.3) |
| >60 |
88 (10.6) |
75 (10.3) |
| Sex | ||
| F | 482 (58.2) | 432 (59.4) |
| M |
346 (41.8) |
295 (40.6) |
| Ethnicity | ||
| Chinese | 94 (11.4) | 90 (12.4) |
| Malay | 374 (45.2) | 331 (45.5) |
| Indian | 353 (42.6) | 299 (41.1) |
| Other |
7 (0.9) |
7 (1.0) |
| Dwelling type | ||
| <3-room public housing | 202 (24.4) | 177 (24.3) |
| 4-room public housing | 360 (43.5) | 310 (42.6) |
| 5-room public housing or
private housing |
266 (32.1) |
240 (33.0) |
| Smoking | ||
| Current smoker | 181 (21.9) | 149 (20.5) |
| Nonsmoker/former smoker |
647 (78.1) |
578 (79.5) |
| No. household members | ||
| 1 | 580 (70.1) | 496 (68.2) |
| 2 | 208 (25.1) | 195 (26.8) |
| 3 | 36 (4.4) | 33 (4.5) |
| 4 |
4 (0.5) |
3 (0.4) |
| Self-reported previous influenza vaccination | ||
| No | 751 (90.7) | 662 (91.1) |
| Yes |
77 (9.3) |
65 (8.9) |
| Employment outside the home | ||
| No | 308 (37.2) | 277 (38.0) |
| Yes |
520 (62.8) |
450 (62.0) |
| Baseline antibody titer | ||
| Mean (SD) | 0.22 (0.71) | 0.25 (0.75) |
| By age group, y | ||
| 20–29 | 0.48 (1.06) | |
| 30–39 | 0.19 (0.58) | |
| 40–49 | 0.17 (0.59) | |
| 50–59 | 0.28 (0.84) | |
| >60 |
0.12 (0.52) |
|
| Public transport | ||
| Seldom | 294 (35.5) | 249 (34.3) |
| Frequent | 534 (64.5) | 478 (65.7) |
*Values are no. (%) except as indicated. Respondents are participants who provided at least 1 blood sample in addition to that obtained at baseline.
