title: A cell culture-derived influenza vaccine provides consistent protection against infection and reduces the duration and severity of disease in infected individuals.
abstract: BACKGROUND
  Current knowledge of the consistency of protection induced by seasonal influenza vaccines over the duration of a full influenza season is limited, and little is known about the clinical course of disease in individuals who become infected despite vaccination.
  
  
  METHODS
  Data from a randomized double-blind placebo-controlled clinical trial undertaken in healthy young adults in the 2008-2009 influenza season were used to investigate the weekly cumulative efficacy of a Vero cell culture-derived influenza vaccine. In addition, the duration and severity of disease in vaccine and placebo recipients with cell culture-confirmed influenza infection were compared.
  
  
  RESULTS
  Vaccine efficacy against matching strains was consistently high (73%-82%) throughout the study, including the entire period of the influenza season during which influenza activity was above the epidemic threshold. Vaccine efficacy was also consistent (68%-83%) when calculated for all strains, irrespective of antigenic match. Vaccination also ameliorated disease symptoms when infection was not prevented. Bivariate analysis of duration and severity showed a significant amelioration of myalgia (P = .003), headache (P = .025), and fatigue (P = .013) in infected vaccinated subjects compared with placebo. Cough (P = .143) and oropharyngeal pain (P = .083) were also reduced in infected vaccinated subjects.
  
  
  CONCLUSIONS
  A Vero cell culture-derived influenza vaccine provides consistently high levels of protection against cell culture-confirmed infection by seasonal influenza virus and significantly reduces the duration and severity of disease in those individuals in which infection is not prevented.
  
  
  BACKGROUND
  ClinicalTrials.gov NCT00566345.
authors.affiliation: Global R&D, Baxter BioScience, Vienna, Austria.
authors.forename: Hartmut J
authors.initials: HJ
authors.lastname: Ehrlich
authors.forename: Julia
authors.initials: J
authors.lastname: Singer
authors.forename: Gregory
authors.initials: G
authors.lastname: Berezuk
authors.forename: Sandor
authors.initials: S
authors.lastname: Fritsch
authors.forename: Gerald
authors.initials: G
authors.lastname: Aichinger
authors.forename: Mary Kate
authors.initials: MK
authors.lastname: Hart
authors.forename: Wael
authors.initials: W
authors.lastname: El-Amin
authors.forename: Daniel
authors.initials: D
authors.lastname: Portsmouth
authors.forename: Otfried
authors.initials: O
authors.lastname: Kistner
authors.forename: P Noel
authors.initials: PN
authors.lastname: Barrett
mesh_terms: D000328:Adult; D000818:Animals; D001709:Biotechnology / Q000379:methods; D018929:Cell Culture Techniques / Q000379:methods; D002522:Chlorocebus aethiops; D004311:Double-Blind Method; D006801:Humans; D007252:Influenza Vaccines / Q000008:administration & dosage / Q000276:immunology*; D007251:Influenza, Human / Q000473:pathology* / Q000517:prevention & control*; D008875:Middle Aged; D010919:Placebos / Q000008:administration & dosage; D012720:Severity of Illness Index; D013678:Technology, Pharmaceutical / Q000379:methods; D013997:Time Factors; D014709:Vero Cells; D055815:Young Adult
chemical_list: D007252:Influenza Vaccines; D010919:Placebos