Muscle size matters: making paediatric vaccination safe for all - a pilot study.

BACKGROUND/OBJECTIVES: Shoulder Injury Related to Vaccine Administration (SIRVA) is an uncommon but clinically significant iatrogenic complication of vaccination, associated with improper injection depth or site selection. This pilot study aimed to evaluate the suitability of existing Australian intramuscular deltoid injection guidelines in a paediatric population and to assess the accuracy of commonly used anatomical landmarking techniques. METHODS: A cohort of 20 participants (14 male, 6 female) aged 12 months to 18 years was recruited. Real-time ultrasound was used to measure the skin-to-deltoid muscle distance and the thickness of the deltoid muscle. These measurements were compared with common external landmarking techniques. RESULTS: Only 20% of participants had sufficient tissue depth to safely accommodate a 25 mm needle. No demographic or anthropometric variables reliably predicted tissue depth. Anatomical landmarking techniques demonstrated variability in accuracy, though all were suitably close to the optimal injection site. CONCLUSIONS: These findings suggest while vaccination landmarking techniques are appropriate, current needle length guidelines in Australia appear to not be appropriate for a paediatric population, and highlight the need for more individualised, evidence-based approaches to vaccine administration.