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Volume 21, Number 4—April 2015
Letter

Avian Influenza A(H7N9) Virus Antibodies in Close Contacts of Infected Persons, China, 2013–2014

Mai-Juan Ma1, Guang-Yuan Ma1, Xiao-Xian Yang1, Shan-Hui Chen1, Gregory C. Gray, Teng Zhao, Jing Bao, Jing-Jing Zhou, Yan-Hua Qian, Bin Lu, Xia Ling2, and Wu-Chun Cao2Comments to Author 
Author affiliations: Beijing Institute of Microbiology and Epidemiology, Beijing, China (M.-J. Ma, W.-C. Cao); Wuxi Center for Disease Control and Prevention, Wuxi, China (G.-Y. Ma, S.-H. Chen, J. Bao, Y.-H. Qian, B. Lu, X. Ling); State Key Laboratory of Pathogen and Biosecurity, Beijing (X.-X. Yang, T. Zhao, J.-J. Zhou); School of Public Health, Central South University, Changsha, China (X.-X. Yang); Duke University Medical Center, Durham, North Carolina, USA (G.C. Gray)

Main Article

Table

Demographic characteristics and HI antibody titers against influenza subtype H7N9, H5N1, H9N2, H1N1, and H3N2 viruses among close contacts of avian influenza A(H7N9)–infected persons, China, 2013–2014*

Characteristics Close contacts, N = 225
Family members, n = 30 Health care workers, n = 177 Others, n = 18
Mean age, y ± SD
 48.03 ± 17.79
 33.71 ± 7.97
 68.50 ± 14.89
Sex
   F 18 (60.0) 135 (76.3) 4 (22.2)
   M
 12 (40.0)
 42 (23.7)
 14 (77.8)
Exposure duration, mean days ± SD
 7.38 ± 4.70
 4.42 ± 3.67
 3 ± 1.48
Virus subtype and HI titer†
   H7N9
<1:80 29 (96.7) 173 (97.7) 18 (100.0)
>1:80 1 (3.3) 4 (2.3) 0
   H5N1
<1:80 30 (100.0) 177 (100.0) 20 (100.0)
>1:80 0 0 0
   H9N2
<1:80 30 (100.0) 177 (100.0) 20 (100.0)
≥1:80 0 0 0
   H1N1
<1:80 30 (100.0) 172 (97.1) 18 (100.0)
>1:80 0 5 (2.9) 0
   H3N2
<1:80 20 (66.7) 89 (50.3) 9 (50.0)
>1:80
 10 (33.3)
 88 (49.7)
 9 (50.0)
MN titer, H7N9‡
<1:10 0 6 (35.3) 1 (100.0)
1:10 0 4 (23.5) 0
1:20 3 (75.0) 3 (17.6) 0
1:40 0 3 (17.6) 0
1:80 1 (25.0) 1 (5.9) 0

*Data are no. (%) unless otherwise indicated. A comparison of HI titers for control serum samples against reference influenza virus strains used in this study is shown in the online Technical Appendix (http://wwwnc.cdc.gov/EID/article/21/4/14-1442-Techapp1.pdf). HI, hemagglutination inhibition; MN, microneutralization assay.
†HI titer cut points were selected conservatively at >1:80 on the basis of World Health Organization recommendations for human infection with influenza A(H5N1) virus (http://www.who.int/influenza/resources/documents/RecAIlabtestsAug07.pdf).
‡Results for 22 close contacts (17 health care workers, 4 family members, and 1 other close contact) with an HI titer of >1:40.

Main Article

1These authors contributed equally to this article.

2These senior authors contributed equally to this article.

Page created: March 17, 2015
Page updated: March 17, 2015
Page reviewed: March 17, 2015
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