Intramuscular Injection Angle: Evidence for Practice?

Abstract
This article presents the findings of a search for evidence to support the 45-60 degree angle of insertion for intramuscular injection of vaccine which is recommended in New Zealand. With the objective of discovering the evidence base for an intramuscular injection angle which differs from that recommended by the World Health Organisation and the accepted practice experienced by the author in the UK, Canada, Malawi and the USA, a comprehensive library and internet literature search was undertaken. As well, information was sought by personal correspondence and contact with a range of immunisation specialists. Both the literature specifically on needle angle and that which includes needle angle within a wider investigation of technique is included. Overwhelmingly the evidence supports a 90 degree angle of needle insertion for intramuscular injection as being that most effective in terms of patient comfort, safety and efficacy of vaccine.   

Keywords
Intramuscular injection technique, vaccine, needle angle, immunisation

Introduction
The issue addressed in this article is the discrepancy between the 45-60 degree needle angle for intramuscular injection of vaccine which is recommended in New Zealand and the standard which is advocated by the WHO and is known by the author’s personal experience to be accepted practice in the UK, Canada, Malawi and the USA. It is argued that a scholarly approach to nursing requires that expert practitioners responsible for their own actions must be able to cite the research evidence to guide their practice - particularly where alternative procedures exist. The purpose of the investigation was to learn the rationale for practice in New Zealand so as to be able to teach this with confidence to trainee vaccinators. Scholarly enquiry challenges assumptions and questions aspects of nursing procedure in order to ensure practice is of the highest possible quality.