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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 WangComments to Author 

Author affiliations: Beijing Center for Disease Prevention and Control, Beijing, People’s Republic of China; Capital Medical University School of Public Health and Family Medicine, Beijing

Main Article

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.

Main Article

1These authors contributed equally to this article.

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