title: Seasonal Influenza Vaccination of Children Induces Humoral and Cell-Mediated Immunity Beyond the Current Season: Cross-reactivity With Past and Future Strains.
abstract: Influenza viruses gradually accumulate point mutations, reducing the effectiveness of prior immune protection.
  
  
  
  Children aged 9-14 years received 2010-2011 trivalent inactivated influenza vaccine (TIV). Vaccination history, hemagglutination-inhibition (HI) titers, and cell-mediated immune responses were assessed to investigate the cross-reactivity with past and future influenza virus strains.
  
  
  
  2010-2011 TIV induced significant T-cell responses and HI titers of ≥160, with a fold-rise of ≥4 and titers of ≥100 maintained for >7 months in the majority of children. Pre-existing memory B cells in these children differentiated quickly to antibody-secreting cells to the new vaccine antigens. Children vaccinated in the previous year maintained high HI titers well into 2010, demonstrating elevated HI titers against A/Perth/16/2009, the future (in 2010-2011) H3N2 component. Prior vaccination enhanced CD8+T-cell responses to A/Perth/16/2009. Children vaccinated with the prior 2009-2010 seasonal vaccine also demonstrated higher preexisting levels of interferon γ-secreting CD4+CD69+T cells to 2009 pandemic influenza A(H1N1). Children previously vaccinated with 2009-2010 seasonal influenza vaccine also showed greater expansion of tumor necrosis factor α-secreting CD8+CD69+T cells to 2009 pandemic influenza A(H1N1) upon vaccination in the 2010-2011 season than those who were not previously vaccinated.
  
  
  
  Seasonal influenza viruses continuously drift, which allows them to circumvent protective immunity, but conserved epitopes provide immunological cross-reactivity in children through either vaccination directly or through prime/boost in the prior influenza season.
authors: Influenza Division, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia.
authors: Adrian J
authors: AJ
authors: Reber
authors: Influenza Division, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia.
authors: Jin Hyang
authors: JH
authors: Kim
authors: Marshfield Clinic Research Foundation, Wisconsin.
authors: Laura A
authors: LA
authors: Coleman
authors: Influenza Division, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia.
authors: Sarah M
authors: SM
authors: Spencer
authors: Influenza Division, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia.
authors: Jessie R
authors: JR
authors: Chung
authors: Influenza Division, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia.
authors: Jufu
authors: J
authors: Chen
authors: Influenza Division, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia.
authors: Paul
authors: P
authors: Gargiullo
authors: Marshfield Clinic Research Foundation, Wisconsin.
authors: Maria E
authors: ME
authors: Sundaram
authors: Marshfield Clinic Research Foundation, Wisconsin.
authors: Edward A
authors: EA
authors: Belongia
authors: Influenza Division, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia.
authors: David K
authors: DK
authors: Shay
authors: Influenza Division, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia.
authors: Jacqueline M
authors: JM
authors: Katz
authors: Influenza Division, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia.
authors: Suryaprakash
authors: S
authors: Sambhara
mesh_terms: D000293:Adolescent; D000914:Antibodies, Viral / Q000097:blood; D002648:Child; D003429:Cross Reactions; D005260:Female; D006385:Hemagglutination Inhibition Tests; D006801:Humans; D007111:Immunity, Cellular; D056724:Immunity, Humoral; D007252:Influenza Vaccines / Q000008:administration & dosage / Q000276:immunology*; D007251:Influenza, Human / Q000276:immunology / Q000517:prevention & control*; D008297:Male; D009975:Orthomyxoviridae / Q000276:immunology*; D013601:T-Lymphocytes / Q000276:immunology; D013997:Time Factors; D015164:Vaccines, Inactivated / Q000008:administration & dosage / Q000276:immunology
chemical_list: D000914:Antibodies, Viral; D007252:Influenza Vaccines; D015164:Vaccines, Inactivated
keywords: B cell; T cell; children; cross-reactivity; hemagglutination inhibition; immune response; influenza; vaccine