title: Randomized trial using ultrasound to assess intramuscular vaccination at a 60° or 90° needle angle.
abstract: OBJECTIVE
  Globally, recommendations differ on the ideal angle of needle insertion to ensure vaccinate deposition in muscle for optimal safety and immunogenicity. This study aimed to compare the level of vaccinate deposition during vaccination, using two different needle angles (60° and 90°), in young children, adolescents and adults.
  
  
  METHODS
  In this randomized cross-over study, two doses of a licensed hepatitis vaccine, were administered to study participants, at a 60° or 90° angle using a fixed template. Ultrasonography was performed with a Philips iu22 ultrasound system. Real time clips and hard copies of images were recorded showing the injection and level of deposition of the vaccinate. Reactogenicity at the site of administration was assessed by participants/parents.
  
  
  RESULTS
  Nineteen participants were enrolled including children, adolescents and adults. Of the total 38 injections performed, 29 (76%) were confirmed by ultrasound as intramuscular (IM), 3 (8%) as not IM, and 6 (16%) unknown. For vaccinations visualised and administered at 60°, 87% (13/15) were intramuscular vs 94.1% (16/17) for those administered at 90°. A body mass index (BMI)≤25 was associated with a higher likelihood of IM injection compared to BMI>25 (p=0.038). There were no differences in reactogenicity for either 60° or 90° angle of administration.
  
  
  CONCLUSIONS
  For the majority of vaccinees, a 60-90° angle of vaccine administration is appropriate for IM deposition of vaccinate. The likelihood of intramuscular deposition is reduced for individuals with a BMI>25. The increasing rates of obesity globally highlight the importance of tailoring vaccination procedures accordingly.
authors.affiliation: Vaccinology and Immunology Research Trials Unit, Women's and Children's Hospital, 72 King William Road, North Adelaide, South Australia, Australia. Helen.marshall@adelaide.edu.au
authors.forename: Helen Siobhan
authors.initials: HS
authors.lastname: Marshall
authors.forename: Michelle Frances
authors.initials: MF
authors.lastname: Clarke
authors.forename: Susan
authors.initials: S
authors.lastname: Evans
authors.forename: Lino
authors.initials: L
authors.lastname: Piotto
authors.forename: Roger J
authors.initials: RJ
authors.lastname: Gent
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D018592:Cross-Over Studies; D057645:Deltoid Muscle / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D007273:Injections, Intramuscular / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009339:Needles; D009765:Obesity / Q000000981:diagnostic imaging; D018084:Ultrasonography, Interventional / Q000379:methods*; D014611:Vaccination / Q000379:methods; D014761:Viral Hepatitis Vaccines / Q000008:administration & dosage*; D055815:Young Adult
chemical_list: D014761:Viral Hepatitis Vaccines