title: Intradermally-administered influenza virus vaccine is safe and immunogenic in healthy adults 18-64 years of age.
abstract: BACKGROUND
  To increase vaccine acceptance, intradermal (ID) influenza vaccine (Fluzone(®) Intradermal, Sanofi Pasteur Inc.) may be an attractive alternative to intramuscular (IM) vaccination due to smaller needle and volume injected.
  
  
  METHODS
  A multicenter, randomized (2:1 ID vs IM vaccines) study, blinded for ID vaccine lots, was conducted among 4292 adults 18-64 years of age enrolled in October 2008. Three lots of investigational trivalent influenza vaccine containing 9μg hemagglutinin (HA) per strain in 0.1mL administered ID with a 30 gauge, 1.5mm long needle were compared to standard dose vaccine (0.5mL containing 15μg HA/strain) given IM.
  
  
  RESULTS
  The post-vaccination antibody geometric mean titers (GMT) for the ID vaccine were similar to the IM vaccine (H1N1: 193.2 vs. 178.3, H3N2: 246.7 vs. 230.7, and B: 102.5 vs. 126.9). Non-inferiority was met for the ID vaccine compared to IM vaccine as assessed by antibody GMT ratios (IM/ID) for all three virus strains (H1N1: 0.92, H3N2: 0.94, and B: 1.24). Seroconversion rates were non-inferior for H1N1 and H3N2, but not for B (ID vs. IM: H1N1: 61.2% vs. 60.5%, H3N2: 75.3% vs. 74.8%, and B: 46.2% vs. 54.2%). Seroprotection (HAI titer ≥1:40) rates were similar between groups (ID vs. IM, H1N1: 91.1% vs. 91.7%, H3N2: 90.7% vs. 91.4%, and B: 87.4% vs. 89.3%). Local injection site reactions overall were more common with ID than IM vaccine (ID vs. IM: 89.2% vs. 60.2%), but were usually grade 1 or 2 and transient. The frequencies of local injection site pain and systemic reactions were similar between vaccine groups, except more myalgia with IM vaccine.
  
  
  CONCLUSIONS
  The ID vaccine elicited immune responses comparable to IM vaccine except for the seroconversion rate to B virus. With the exception of pain, local injection site reactions were more common with the ID vaccine, but well-tolerated and of short duration.
  
  
  BACKGROUND
  ClinicalTrials.gov identifier: NCT00772109.
authors.affiliation: Saint Louis University School of Medicine, 1100 South Grand Blvd. (DRC-8th floor), St. Louis, MO 63104, USA. gorsegj@slu.edu
authors.forename: Geoffrey J
authors.initials: GJ
authors.lastname: Gorse
authors.forename: Ann R
authors.initials: AR
authors.lastname: Falsey
authors.forename: John A
authors.initials: JA
authors.lastname: Fling
authors.forename: Terry L
authors.initials: TL
authors.lastname: Poling
authors.forename: Cynthia B
authors.initials: CB
authors.lastname: Strout
authors.forename: Peter H
authors.initials: PH
authors.lastname: Tsang
mesh_terms: D000293:Adolescent; D000328:Adult; D000914:Antibodies, Viral; D000917:Antibody Formation; D004311:Double-Blind Method; D005260:Female; D006385:Hemagglutination Inhibition Tests; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype / Q000276:immunology*; D053122:Influenza A Virus, H3N2 Subtype / Q000276:immunology*; D009981:Influenza B virus / Q000276:immunology*; D007252:Influenza Vaccines / Q000008:administration & dosage / Q000009:adverse effects / Q000276:immunology*; D007251:Influenza, Human / Q000517:prevention & control*; D007271:Injections, Intradermal; D007273:Injections, Intramuscular; D008297:Male; D008875:Middle Aged; D010146:Pain; D014611:Vaccination; D055815:Young Adult
chemical_list: D000914:Antibodies, Viral; D007252:Influenza Vaccines