title: Human Infection with Influenza A(H7N9) Virus during 3 Major Epidemic Waves, China, 2013-2015.
abstract: Since March 2013, a novel influenza A(H7N9) virus has caused 3 epidemic waves of human infection in mainland China. We analyzed data from patients with laboratory-confirmed influenza A(H7N9) virus infection to estimate the risks for severe outcomes after hospitalization across the 3 waves. We found that hospitalized patients with confirmed infections in waves 2 and 3 were younger and more likely to be residing in small cities and rural areas than were patients in wave 1; they also had a higher risk for death, after adjustment for age and underlying medical conditions. Risk for death among hospitalized patients during waves 2 and 3 was lower in Jiangxi and Fujian Provinces than in eastern and southern provinces. The variation in risk for death among hospitalized case-patients in different areas across 3 epidemic waves might be associated with differences in case ascertainment, changes in clinical management, or virus genetic diversity.
authors.forename: Peng
authors.initials: P
authors.lastname: Wu
authors.forename: Zhibin
authors.initials: Z
authors.lastname: Peng
authors.forename: Vicky J
authors.initials: VJ
authors.lastname: Fang
authors.forename: Luzhao
authors.initials: L
authors.lastname: Feng
authors.forename: Tim K
authors.initials: TK
authors.lastname: Tsang
authors.forename: Hui
authors.initials: H
authors.lastname: Jiang
authors.forename: Eric H Y
authors.initials: EH
authors.lastname: Lau
authors.forename: Juan
authors.initials: J
authors.lastname: Yang
authors.forename: Jiandong
authors.initials: J
authors.lastname: Zheng
authors.forename: Ying
authors.initials: Y
authors.lastname: Qin
authors.forename: Zhongjie
authors.initials: Z
authors.lastname: Li
authors.forename: Gabriel M
authors.initials: GM
authors.lastname: Leung
authors.forename: Hongjie
authors.initials: H
authors.lastname: Yu
authors.forename: Benjamin J
authors.initials: BJ
authors.lastname: Cowling
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D002648:Child; D002675:Child, Preschool; D002681:China / Q000453:epidemiology; D004196:Disease Outbreaks; D005260:Female; D005838:Genotype; D062306:Geography, Medical; D049674:History, 21st Century; D006760:Hospitalization; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D064766:Influenza A Virus, H7N9 Subtype / Q000145:classification / Q000235:genetics*; D007251:Influenza, Human / Q000453:epidemiology* / Q000266:history / Q000635:transmission / Q000821:virology*; D008297:Male; D008875:Middle Aged; D009026:Mortality; D011159:Population Surveillance; D055815:Young Adult
keywords: China; clinical severity; epidemiology; influenza; influenza A(H7N9); respiratory infections; viruses