Volume 16, Number 10—October 2010
Research
Risk Factors for Pandemic (H1N1) 2009 Virus Seroconversion among Hospital Staff, Singapore
Table 1
Selected characteristics of healthcare workers by seroconversion status for pandemic (H1N1) 2009, Singapore, 2009*
Characteristic |
No. (%) seroconverters, n = 35 |
No. (%) nonseroconverters, n = 496 |
p value |
Baseline sample timing | 0.20† | ||
Jun 22–26 | 17 (49) | 187 (38) | |
Jun 28–Jul 7 |
18 (51) |
309 (62) |
|
Follow-up samples taken | 0.73† | ||
Intraepidemic only | 3 (9) | 65 (13) | |
Postepidemic only | 2 (6) | 31 (6) | |
Intraepidemic and postepidemic |
30 (86) |
400 (81) |
|
Female |
30 (86) |
411 (83) |
0.66† |
Seasonal influenza vaccination | 34 (97) | 449 (91) | 0.19† |
ARI episode‡ | 22 (63) | 75 (15) | <0.01† |
FRI episode‡ |
18 (51) |
41 (8) |
<0.01† |
Age, y, mean (95% CI) | 35 (31–39) | 34 (33–35) | 0.76§ |
GMT for baseline sample (95% CI) | 5.9 (5.3–6.5) | 7.8 (7.3–8.3) | 0.02§ |
*ARI, acute respiratory illness; FRI, febrile respiratory illness; CI, confidence interval; GMT, geometric mean titer.
†χ2 test comparing seroconverters and nonseroconverters.
‡Healthcare workers who seroconverted are considered to have had an ARI or FRI episode if the date of onset preseded the date when seroconversion was detected.
§Student t test comparing seroconverters and nonseroconverters.