title: Immunogenicity and safety of quadrivalent versus trivalent inactivated influenza vaccine: a randomized, controlled trial in adults.
abstract: BACKGROUND
  Two phylogenetic lineages of influenza B virus coexist and circulate in the human population (B/Yamagata and B/Victoria) but only one B-strain is included in each seasonal vaccine. Mismatch regularly occurs between the recommended and circulating B-strain. Inclusion of both lineages in vaccines may offer better protection against influenza.
  
  
  METHODS
  This study (NCT00714285) assessed the immunogenicity and safety of two candidate quadrivalent influenza vaccines (QIV) containing two A- and two B-strains (one from each lineage) in adults (18-60 years). Subjects were randomized and stratified by age to receive either QIV (non-adjuvanted or low-dose adjuvanted [LD QIV-AS]) or trivalent influenza vaccine (TIV, non-adjuvanted or low-dose adjuvanted [LD TIV-AS]), N = 105 in all treatment groups. The study evaluated the statistical non-inferiority of the immunological response elicited by QIV and LD QIV-AS versus TIV and LD TIV-AS and the statistical superiority of the response elicited by the quadrivalent vaccines against the B-strain (B/Jiangsu) not included in the TIV.
  
  
  RESULTS
  Pre-defined non-inferiority and superiority criteria were reached for both QIVs compared to the TIVs. On Day 21 in all vaccine groups SCRs were ≥54.8%, SPRs ≥88.5% and SCFs ≥5.4 for the A strains and B strain included in all vaccines (B/Malaysia). This fulfilled the European (CHMP) and the US (CBER) licensing criteria for the assessment of influenza vaccines in adults (CHMP criteria: SCR > 40%, SPR > 70%, SCF > 2; CBER criteria: LL of 95% CI for SPR ≥ 70% or SCR ≥ 40%). Only the QIVs met the CHMP and CBER criteria for the B/Jiangsu strain. In the QIV and LD-QIV-AS groups, the SCFs were 9.1 and 8.1, respectively and the SPRs were 98.1% and 95.2%, whereas for the TIV and LD-TIV-AS groups, the SCFs were 2.3 and 2.5, respectively, and the SPRs were 75.0% and 63.8%, with the LLs of the 95% CI <70% for SPR and <40% for SCR.
  
  
  CONCLUSIONS
  Addition of a fourth strain did not impact the immune response elicited by the three original strains contained in the TIV. A clear immunological benefit was seen with the QIV formulation for the second B-strain, indicating that quadrivalent vaccines could provide broader protection against influenza.
  
  
  BACKGROUND
  ClinicalTrials.gov: NCT00714285.
authors.affiliation: The Vaccination and Travel Medicine Center, Poliklinika II, Bratří Štefanu 895, Hradec Králové 500 03, Czech Republic. jiri.beran@vakcinace.cz
authors.forename: Jiří
authors.initials: J
authors.lastname: Beran
authors.forename: Mathieu
authors.initials: M
authors.lastname: Peeters
authors.forename: Walthère
authors.initials: W
authors.lastname: Dewé
authors.forename: Jolana
authors.initials: J
authors.lastname: Raupachová
authors.forename: Lenka
authors.initials: L
authors.lastname: Hobzová
authors.forename: Jeanne-Marie
authors.initials: JM
authors.lastname: Devaster
mesh_terms: D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D000914:Antibodies, Viral / Q000097:blood; D005260:Female; D006385:Hemagglutination Inhibition Tests; D006801:Humans; D009980:Influenza A virus / Q000276:immunology; D009981:Influenza B virus / Q000276:immunology; D007252:Influenza Vaccines / Q000008:administration & dosage / Q000009:adverse effects* / Q000276:immunology*; D007251:Influenza, Human / Q000276:immunology* / Q000517:prevention & control*; D008297:Male; D008875:Middle Aged; D009500:Neutralization Tests
chemical_list: D000914:Antibodies, Viral; D007252:Influenza Vaccines