Optimal technique for intramuscular injection of infants and toddlers: a randomised trial

Objective: To compare the rates of adverse reactions and parental approval ratings for three different techniques for anterolateral thigh vaccination in children aged 2, 4, 6 and 18 months. Design: Randomised, observer-blind trial. Participants: 375 children who received pertussis-containing vaccines in a regional New South Wales town between 29 May 2001 and 30 June 2002. Interventions: Children were randomised to receive intramuscular injection with acellular pertussis-containing and Haemophilus influenzae type b vaccines with one of three recognised injection techniques (Australian, World Health Organization or United States). Main outcome measures: Local adverse reactions (bruising and redness/swelling), systemic adverse reactions (irritability, perceived fever, persistent crying/screaming, drowsiness, vomiting/poor feeding) and parental acceptance were assessed 24 hours after injection. Results: 361 children (96%) were evaluated 24 hours after vaccination. The WHO technique resulted in significantly fewer children, than with the other two techniques, with the systemic adverse reaction variable "irritability" (P = 0.0039). There was a significant difference between the technique groups overall for the local adverse reaction "bruising" with acellular pertussis-containing vaccines (P = 0.0418), due to a lower reaction rate in the WHO group compared with the US group (P = 0.0356). Conclusion: The WHO technique appears to be the optimal technique for anterolateral thigh injection in children - it ensures that the injection is intramuscular, results in fewer adverse reactions, and is the easiest technique to perform as it does not require angling of the needle to the long axis of the femur.