Extract:
“The standard needle length for deltoid intramuscular injection is 25 mm. Unfortunately, for up to 45% of adults with obesity, the standard needle can be inadequate to ensure intramuscular deposition of vaccine, with the specific deltoid injection site location also influencing the depth the needle must penetrate to reach muscle. The global prevalence of obesity is high and increasing, so evidence-based advice on how to select the optimal needle length for people receiving intramuscular vaccines is needed. However, there is only a small evidence base to reliably identify vaccine recipient characteristics that can be used to choose individuals who might require a longer needle, and an absence of specific recommendations in immunisation guidelines.”
Reference:Doppen M, Kearns C, Hills T, Weatherall M, Beasley R. Intramuscular vaccination needle length: a call to arms. Lancet. 2024 Feb 10;403(10426):528-529. doi: 10.1016/S0140-6736(23)02222-5. PMID: 38341247.