title: Cell-Mediated Immunity Against Antigenically Drifted Influenza A(H3N2) Viruses in Children During a Vaccine Mismatch Season.
abstract: Emergence of antigenically drifted influenza A(H3N2) viruses resulted in reduced vaccine effectiveness in all age groups during the 2014-2015 influenza season. In children, inactivated influenza vaccine (IIV) elicited neutralizing antibodies (Abs) against drifted strains at significantly lower levels than against the vaccine strain. Little is known about the cross-reactivity of cell-mediated immunity against drifted strains in children.
  
  
  
  Children aged 3-17 years (n = 48) received IIV during the 2014-2015 influenza season. Peripheral blood mononuclear cells, collected before (on day 0) and after (on days 7 and 21) vaccination were evaluated for induction of cross-reactive plasmablasts, memory B cells, and cytokine-secreting CD4(+) and CD8(+) T cells against the vaccine and drifted A(H3N2) viruses by an enzyme-linked immunospot assay and flow cytometry.
  
  
  
  IIV increased frequencies of plasmablasts and memory B cells. The overall induction of the T-cell response was not significant. Both B-cell and T-cell responses showed significant cross-reactivity against A(H3N2) viruses. Age and preexisting immunity affected virus-specific plasmablast responses and fold-change of T-cell responses, respectively. The proportion of T-helper type 1-prone (ie, interferon γ- or tumor necrosis factor α-secreting) CD4(+) T cell responses also increased with age.
  
  
  
  In children aged 3-17 years, B- and T-cell responses following IIV receipt showed significant cross-reactivity against A(H3N2) viruses during a vaccine mismatch season.
authors.affiliation: Influenza Division, Centers for Disease Control and Prevention.
authors.forename: Jin Hyang
authors.initials: JH
authors.lastname: Kim
authors.affiliation: Batelle Memorial Institute.
authors.forename: Margarita
authors.initials: M
authors.lastname: Mishina
authors.affiliation: Atlanta Research and Education Foundation, Georgia.
authors.forename: Jessie R
authors.initials: JR
authors.lastname: Chung
authors.affiliation: Department of Immunology Center for Vaccine Research.
authors.forename: Kelly Stefano
authors.initials: KS
authors.lastname: Cole
authors.affiliation: Department of Family Medicine.
authors.forename: Mary Patricia
authors.initials: MP
authors.lastname: Nowalk
authors.affiliation: Department of Pediatrics, University of Pittsburgh Children's Hospital of Pittsburgh, Pennsylvania.
authors.forename: Judith M
authors.initials: JM
authors.lastname: Martin
authors.affiliation: Atlanta Research and Education Foundation, Georgia.
authors.forename: Sarah
authors.initials: S
authors.lastname: Spencer
authors.affiliation: Influenza Division, Centers for Disease Control and Prevention.
authors.forename: Brendan
authors.initials: B
authors.lastname: Flannery
authors.affiliation: Department of Family Medicine.
authors.forename: Richard K
authors.initials: RK
authors.lastname: Zimmerman
authors.affiliation: Influenza Division, Centers for Disease Control and Prevention.
authors.forename: Suryaprakash
authors.initials: S
authors.lastname: Sambhara
mesh_terms: D000293:Adolescent; D001402:B-Lymphocytes / Q000276:immunology*; D002648:Child; D002675:Child, Preschool; D003429:Cross Reactions; D005260:Female; D040961:Genetic Drift; D006801:Humans; D064789:Immunity, Heterologous; D053122:Influenza A Virus, H3N2 Subtype / Q000235:genetics / Q000276:immunology*; D007251:Influenza, Human / Q000276:immunology* / Q000821:virology*; D008297:Male; D013601:T-Lymphocytes / Q000276:immunology*
keywords: A(H3N2) drifted viruses; antigenic mismatch; cell-mediated immunity; influenza vaccines; young and adolescent children