title: Interim estimates of divergence date and vaccine strain match of human influenza A(H3N2) virus from systematic influenza surveillance (2010-2015) in Hangzhou, southeast of China.
abstract: OBJECTIVE
  In the post-pandemic period 2010-2015, seasonal influenza A(H3N2) virus predominated in Hangzhou, southeast of China, with an increased activity and semi-annual seasons. This study utilized HA virus gene segment sequences to analyze the divergence date and vaccine strain match of human influenza A(H3N2) virus from systematic influenza surveillance in Hangzhou.
  
  
  METHODS
  Virological and serological analyses of 124 representative A(H3N2) viruses from prospective studies of systematic surveillance samples were conducted to quantify the genetic and antigenic characteristics and their vaccine strain match.
  
  
  RESULTS
  Bayesian phylogenetic inference showed that two separate subgroups 3C.3 and 3C.2 probably diverged from group 3C in early 2012 and then evolved into groups 3C.3a and 3C.2a, respectively, in the 2014/15 influenza season. Furthermore, high amino acid substitution rates of the HA1 subunit were found in A(H3N2) group 3C.2a variants, indicating that increased antigenic drift of A(H3N2) group 3C.2a virus is associated with a vaccine mismatch to the 2015/16 vaccine reference strain Switzerland/9715293/2013 (group 3C.3a).
  
  
  CONCLUSIONS
  A portion of the group 3C.2a isolates are not covered by the current A(H3N2) vaccine strain. These findings offer insights into the emergence of group 3C.2a variants with epidemic potential in the imminent influenza seasons.
authors.affiliation: Microbiology Laboratory, Hangzhou Center for Disease Control and Prevention, No. 568 Mingshi Road, Jianggan District, Hangzhou City, Zhejiang 310021, China. Electronic address: 10407030@zju.edu.cn.
authors.forename: Jun
authors.initials: J
authors.lastname: Li
authors.affiliation: Microbiology Laboratory, Hangzhou Center for Disease Control and Prevention, No. 568 Mingshi Road, Jianggan District, Hangzhou City, Zhejiang 310021, China.
authors.forename: Yin-yan
authors.initials: YY
authors.lastname: Zhou
authors.affiliation: Microbiology Laboratory, Hangzhou Center for Disease Control and Prevention, No. 568 Mingshi Road, Jianggan District, Hangzhou City, Zhejiang 310021, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Kou
authors.affiliation: Microbiology Laboratory, Hangzhou Center for Disease Control and Prevention, No. 568 Mingshi Road, Jianggan District, Hangzhou City, Zhejiang 310021, China.
authors.forename: Xin-fen
authors.initials: XF
authors.lastname: Yu
authors.affiliation: Microbiology Laboratory, Hangzhou Center for Disease Control and Prevention, No. 568 Mingshi Road, Jianggan District, Hangzhou City, Zhejiang 310021, China.
authors.forename: Zhi-bei
authors.initials: ZB
authors.lastname: Zheng
authors.affiliation: Department of Infectious Diseases, Hangzhou Center for Disease Control and Prevention, Zhejiang, China.
authors.forename: Xu-hui
authors.initials: XH
authors.lastname: Yang
authors.affiliation: Microbiology Laboratory, Hangzhou Center for Disease Control and Prevention, No. 568 Mingshi Road, Jianggan District, Hangzhou City, Zhejiang 310021, China.
authors.forename: Hao-qiu
authors.initials: HQ
authors.lastname: Wang
mesh_terms: D001499:Bayes Theorem; D002681:China / Q000453:epidemiology; D019267:Hemagglutinin Glycoproteins, Influenza Virus / Q000235:genetics*; D006801:Humans; D053122:Influenza A Virus, H3N2 Subtype / Q000235:genetics* / Q000276:immunology*; D007252:Influenza Vaccines / Q000276:immunology*; D007251:Influenza, Human / Q000453:epidemiology / Q000517:prevention & control* / Q000821:virology; D010802:Phylogeny; D011159:Population Surveillance; D011446:Prospective Studies; D012621:Seasons
chemical_list: D019267:Hemagglutinin Glycoproteins, Influenza Virus; D007252:Influenza Vaccines
keywords: Antigenic drift; Divergence; H3N2; Influenza A; Vaccine match