title: Intradermal influenza vaccine administered using a new microinjection system produces superior immunogenicity in elderly adults: a randomized controlled trial.
abstract: BACKGROUND
  Enhanced influenza vaccines are needed to provide improved protection for elderly individuals. The intradermal vaccination route was hypothesized to provide immunogenicity superior to that provided by the intramuscular vaccination route.
  
  
  METHODS
  In a multicenter, randomized study, 1107 volunteers >60 years of age received intradermal trivalent inactivated influenza vaccine containing 15 or 21 microg of hemagglutinin per strain or intramuscular control vaccine. Intradermal vaccines used a novel microinjection system designed to ensure easy, convenient, consistent vaccination. The primary end points of the study were the strain-specific hemagglutination inhibition geometric mean titers (GMTs) noted 21 days after vaccination. Groups were compared using noninferiority and superiority analyses.
  
  
  RESULTS
  For each strain, the GMTs noted in association with each intradermal vaccine were superior to those noted with the intramuscular control (adjusted P< .0001). Seroprotection rates, seroconversion rates, and mean titer increases were also superior for intradermally administered vaccine in all but one of the analyses undertaken. Systemic reactogenicity was comparable between routes. Local injection site reactions, particularly erythema but not pain, were more commonly associated with intradermal vaccination.
  
  
  CONCLUSIONS
  For the first time, the intradermal vaccination route has been used to elicit immune responses significantly superior to those noted in association with the conventional intramuscular vaccination route. This was done using an easy-to-use, reliable microinjection system. This superior response is expected to enhance annual protection against influenza in this vulnerable population.
  
  
  BACKGROUND
  Clinicaltrials.gov registry number: NCT00296829.
authors.affiliation: Centre for Clinical Research and Effective Practice, Middlemore Hospital, Auckland, New Zealand. holland@middlemore.co.nz
authors.forename: David
authors.initials: D
authors.lastname: Holland
authors.forename: Robert
authors.initials: R
authors.lastname: Booy
authors.forename: Ferdinandus
authors.initials: F
authors.lastname: De Looze
authors.forename: Peter
authors.initials: P
authors.lastname: Eizenberg
authors.forename: James
authors.initials: J
authors.lastname: McDonald
authors.forename: Jeff
authors.initials: J
authors.lastname: Karrasch
authors.forename: Maureen
authors.initials: M
authors.lastname: McKeirnan
authors.forename: Hatem
authors.initials: H
authors.lastname: Salem
authors.forename: Graham
authors.initials: G
authors.lastname: Mills
authors.forename: Jim
authors.initials: J
authors.lastname: Reid
authors.forename: Françoise
authors.initials: F
authors.lastname: Weber
authors.forename: Melanie
authors.initials: M
authors.lastname: Saville
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000276:immunology*; D004306:Dose-Response Relationship, Immunologic; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007252:Influenza Vaccines / Q000008:administration & dosage* / Q000009:adverse effects / Q000276:immunology*; D007251:Influenza, Human / Q000276:immunology* / Q000517:prevention & control; D007271:Injections, Intradermal / Q000295:instrumentation; D008297:Male; D008845:Microinjections; D008875:Middle Aged; D015164:Vaccines, Inactivated / Q000008:administration & dosage / Q000009:adverse effects / Q000276:immunology
chemical_list: D007252:Influenza Vaccines; D015164:Vaccines, Inactivated