title: Assessing Change in Avian Influenza A(H7N9) Virus Infections During the Fourth Epidemic - China, September 2015-August 2016.
abstract: Since human infections with avian influenza A(H7N9) virus were first reported by the Chinese Center for Disease Control and Prevention (China CDC) in March 2013 (1), mainland China has experienced four influenza A(H7N9) virus epidemics. Prior investigations demonstrated that age and sex distribution, clinical features, and exposure history of A(H7N9) virus human infections reported during the first three epidemics were similar (2). In this report, epidemiology and virology data from the most recent, fourth epidemic (September 2015-August 2016) were compared with those from the three earlier epidemics. Whereas age and sex distribution and exposure history in the fourth epidemic were similar to those in the first three epidemics, the fourth epidemic demonstrated a greater proportion of infected persons living in rural areas, a continued spread of the virus to new areas, and a longer epidemic period. The genetic markers of mammalian adaptation and antiviral resistance remained similar across each epidemic, and viruses from the fourth epidemic remained antigenically well matched to current candidate vaccine viruses. Although there is no evidence of increased human-to-human transmissibility of A(H7N9) viruses, the continued geographic spread, identification of novel reassortant viruses, and pandemic potential of the virus underscore the importance of rigorous A(H7N9) virus surveillance and continued risk assessment in China and neighboring countries.
authors.forename: Nijuan
authors.initials: N
authors.lastname: Xiang
authors.forename: Xiyan
authors.initials: X
authors.lastname: Li
authors.forename: Ruiqi
authors.initials: R
authors.lastname: Ren
authors.forename: Dayan
authors.initials: D
authors.lastname: Wang
authors.forename: Suizan
authors.initials: S
authors.lastname: Zhou
authors.forename: Carolyn M
authors.initials: CM
authors.lastname: Greene
authors.forename: Ying
authors.initials: Y
authors.lastname: Song
authors.forename: Lei
authors.initials: L
authors.lastname: Zhou
authors.forename: Lei
authors.initials: L
authors.lastname: Yang
authors.forename: C Todd
authors.initials: CT
authors.lastname: Davis
authors.forename: Ye
authors.initials: Y
authors.lastname: Zhang
authors.forename: Yali
authors.initials: Y
authors.lastname: Wang
authors.forename: Jian
authors.initials: J
authors.lastname: Zhao
authors.forename: Xiaodan
authors.initials: X
authors.lastname: Li
authors.forename: A Danielle
authors.initials: AD
authors.lastname: Iuliano
authors.forename: Fiona
authors.initials: F
authors.lastname: Havers
authors.forename: Sonja J
authors.initials: SJ
authors.lastname: Olsen
authors.forename: Timothy M
authors.initials: TM
authors.lastname: Uyeki
authors.forename: Eduardo
authors.initials: E
authors.lastname: Azziz-Baumgartner
authors.forename: Susan
authors.initials: S
authors.lastname: Trock
authors.forename: Bo
authors.initials: B
authors.lastname: Liu
authors.forename: Haitian
authors.initials: H
authors.lastname: Sui
authors.forename: Xu
authors.initials: X
authors.lastname: Huang
authors.forename: Yanping
authors.initials: Y
authors.lastname: Zhang
authors.forename: Daxin
authors.initials: D
authors.lastname: Ni
authors.forename: Zijian
authors.initials: Z
authors.lastname: Feng
authors.forename: Yuelong
authors.initials: Y
authors.lastname: Shu
authors.forename: Qun
authors.initials: Q
authors.lastname: Li
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D002648:Child; D002675:Child, Preschool; D002681:China / Q000453:epidemiology; D024882:Drug Resistance, Viral / Q000235:genetics; D058872:Epidemics / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D064766:Influenza A Virus, H7N9 Subtype / Q000235:genetics / Q000302:isolation & purification; D007251:Influenza, Human / Q000453:epidemiology* / Q000821:virology*; D008297:Male; D008875:Middle Aged; D012424:Rural Population / Q000706:statistics & numerical data; D017678:Sex Distribution; D013997:Time Factors; D055815:Young Adult