One Vaccination Needle Size Does Not Fit All: MRINZ Research Revealed in The Lancet

The Medical Research Institute of New Zealand (MRINZ) has unveiled crucial knowledge of how to determine  the necessary needle length for successful intramuscular (IM) deposition of vaccines. A Research Review, titled 'IM Vaccination Needle Length: A Call To Arms,' was published in the esteemed medical journal, The Lancet.

The research reveals that the standard 25 mm needle may fail to ensure successful intramuscular (IM) deposition of vaccines in a significant number of adults, especially in up to 45% of obese individuals.

Most vaccines, including COVID-19, are approved for IM injection in the deltoid muscle. MRINZ's two-year programme, using ultrasound measurements, identifies arm circumference and BMI as indicators for selecting the right needle length to ensure successful IM vaccination. For the recommended New Zealand deltoid site, a 38mm needle is preferred for arm circumferences larger than 35cm (men) and 30cm (women), addressing a critical gap in immunisation guidelines.

Professor Richard Beasley, MRINZ Director, emphasises the need for clear guidance, as vague terms like 'large arms' may result in suboptimal vaccine delivery. The research provides evidence-based recommendations, especially for individuals with obesity who are at a higher risk.

With global obesity rates rising, affecting about one-third of adults in Aotearoa New Zealand and Australia, using the right needle length is a public health priority. While the findings hold national significance for updating New Zealand's guidance, ongoing research is crucial to establishing measurement frameworks for optimal vaccine delivery worldwide. The study marks a significant step towards precision in vaccination administration on a global scale.

READ THE FULL PRESS RELEASE HERE.