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Volume 22, Number 6—June 2016
CME ACTIVITY - Synopsis

Human Infection with Influenza A(H7N9) Virus during 3 Major Epidemic Waves, China, 2013–2015

Peng Wu1, Zhibin Peng1, Vicky J. Fang, Luzhao Feng, Tim K. Tsang, Hui Jiang, Eric H.Y. Lau, Juan Yang, Jiandong Zheng, Ying Qin, Qiao Sun, Gabriel M. Leung, Sheng WeiComments to Author , and Benjamin J. Cowling
Author affiliations: World Health Organization Collaborating Centre for Infectious Disease Epidemiology and Control, School of Public Health, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong, China (P. Wu, V.J. Fang, T.K. Tsang, E.H.Y. Lau, G.M. Leung, B.J. Cowling); Division of Infectious Disease, Key Laboratory of Surveillance and Early-warning on Infectious Disease, Chinese Center for Disease Control and Prevention, Beijing, China (Z. Peng, L. Feng, H. Jiang, J. Yang, J. Zheng, Y. Qin, Z. Li, H. Yu)

Main Article

Table 1

Characteristics of laboratory-confirmed influenza A(H7N9) cases detected in 3 epidemic waves, China, 2013–2015

Characteristic No. (%) cases
Wave 1A, Jan 2013–Mar 2013, n = 19 Wave 1B, Apr 2013–Sep 2013, n = 115 Wave 2, Oct 2013–Sep 2014, n = 306 Wave 3, Oct 2014–Mar 2015, n = 215
Age group, y
0–15 1 (5) 6 (5) 19 (6) 17 (8)
16–59 8 (42) 47 (41) 151 (49) 113 (53)
60–74 8 (42) 37 (32) 89 (29) 58 (27)
>75 2 (11) 25 (22) 47 (15) 27 (13)
Median
60
61
57
56
Male sex
13 (68)
81 (70)
212 (69)
154 (72)
Residence*
Provincial capital or municipality 10 (53) 58 (50) 57 (19) 22 (10)
Other cities 6 (32) 23 (20) 131 (43) 100 (47)
Rural areas
3 (16)
34 (30)
118 (39)
93 (43)
Presence of ≥1 underlying medical condition†
10 (53)
42 (37)
91 (30)
64 (30)
Onset to hospital admission, d
0–2 2 (11) 12 (10) 41 (14) 32 (18)
3–6 8 (44) 62 (54) 151 (52) 84 (46)
>7
8 (44)
41 (36)
96 (33)
65 (36)
Poultry exposure
Any exposure to poultry 15 (79) 91 (83) 165 (81) 116 (74)
Occupational exposure to live poultry 1 (5) 6 (5) 21 (7) 22 (10)
Visited live poultry market 12 (63) 62 (54) 132 (61) 105 (67)
Exposure to sick or dead poultry 0 (0) 3 (3) 3 (1) 7 (5)
Exposure to backyard poultry 6 (35) 48 (49) 34 (20) 4 (2)

*For more information, see the online Technical Appendix (http://wwwnc.cdc.gov/EID/article/22/6/15-1752-Techapp1.pdf).
†Only underlying medical disorders associated with a high risk for influenza complications were counted here, including chronic respiratory disease, asthma, chronic cardiovascular disease, diabetes, chronic liver disease, chronic kidney disease, immunosuppressed status, and neuromuscular disorders.

Main Article

1These authors contributed equally to this article.

Page created: May 12, 2016
Page updated: May 12, 2016
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