Volume 17, Number 10—October 2011
Research
Pandemic (H1N1) 2009 among Quarantined Close Contacts, Beijing, People’s Republic of China
Xinghuo Pang1, Peng Yang1, Shuang Li, Li Zhang, Lili Tian, Yang Li, Bo Liu, Yi Zhang, Baiwei Liu, Ruogang Huang, Xinyu Li, and Quanyi Wang
Table 3
Attack rate for pandemic (H1N1) 2009, including subclinical infection, by characteristics of index case-patients and close contacts, Beijing, People’s Republic of China
| Characteristic | Attack rate, % (no. infected/total contacts) | χ2 p value |
|---|---|---|
| Overall | 2.4 (167/7,099) | NA* |
| Index case-patient | ||
| Sex | ||
| M | 2.2 (91/4,192) | 0.225 |
| F | 2.6 (76/2,907) | |
| Age, y | ||
| 0–19 | 2.7 (113/4,144) | 0.022 |
| 20–50 | 1.9 (52/2,680) | |
| >50 | 0.7 (2/275) | |
| Infection source | ||
| Imported case | 2.5 (125/5,049) | 0.282 |
| Community-acquired case | 2.0 (42/2,050) | |
| By type of exposure | ||
| Exposure to symptomatic index case-patient in symptomatic phase | 3.1 (135/4,305) | <0.001 |
| Exposure to symptomatic index case-patient before illness onset | 1.2 (32/2,642) | |
| Exposure to subclinical index case-patient | 0 (0/149) | |
| Close contacts | ||
| Sex | ||
| M | 2.3 (82/3,518) | 0.808 |
| F | 2.4 (85/3,514) | |
| Age, y | ||
| 0–19 | 4.5 (82/1,837) | <0.001 |
| 20–50 | 2.4 (78/3,299) | |
| >50 | 0.8 (7/843) | |
| Relationship to index case-patient | ||
| Spouse | 5.3 (4/75) | <0.001 |
| Other household member | 6.6 (52/786) | |
| Nonrelated roommate | 2.5 (9/367) | |
| Contact at workplace or school | 3.0 (49/1,610) | |
| Nonhousehold relative | 2.8 (5/177) | |
| Passenger on the same flight | 0.9 (28/3,129) | |
| Friend | 3.6 (19/523) | |
| Service person met at public place | 0.2 (1/432) | |
| Flight time for passenger on the same flight, h | ||
| <12 | 0.4 (8/1,846) | 0.001 |
| >12 | 1.6 (20/1,283) | |
| Exposure duration of nonpassenger close contact, h | ||
| <12 | 1.9 (38/2,054) | <0.001 |
| >12 | 5.3 (101/1,912)
*Not available. *Not available. |
*Not available.
1These authors contributed equally to this article.
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