Thank you for inviting us to comment on Dr Cimolai’s letter. Vaccine safety, including injection safety, is important to the public, immunizers, and public health. In this regard, we produce immunization updates regularly[1 [10]] with administration advice based on provincial guidance.[2 [11]] This advice is consistent with national and US recommendations.[3,4 [12]]

While vaccines are very safe, an injection given in the wrong place can cause a nerve or joint injury. An intramuscular injection given too high in the deltoid can injure the shoulder joint/bursa; those given too low can injure a branch of the axillary nerve. These complications are preventable if the correct landmarking technique is followed. 

Radial nerve injury following subcutaneous and intramuscular injection in the outer triceps area, or radial nerve injury following intramuscular injection in the deltoid, is highly unusual. We receive approximately 150 reports of adverse events following immunization annually, but we do not recall a single report of radial nerve injury. A correctly landmarked intramuscular injection of the deltoid should not result in injury to the radial nerve (a graphic showing the course of the radial nerve is available at www.medicineplexus.com/index.php/articles/86-radial-nerve [13] [5 [14]]). The radial nerve courses on the posterior axillary wall, and then runs through the spiral groove between lateral and medial heads of the triceps; thus, it does not have exposure in the deltoid area. In addition, the outer triceps area is reserved for subcutaneous procedures only. A vaccine given outside the recommended area of the deltoid or given incorrectly (intramuscular instead of subcutaneous) in the outer triceps area could result in a radial nerve injury. The remedy here is not to change injection site recommendations but rather to correct the injection technique.

We recommend all physicians follow local health authority/provincial guidance in immunizing patients and invite physicians to report adverse events to local public health centres.[6 [15]] Vaccine safety surveillance is an important partnership between primary care providers and public health. We appreciate the opportunity to promote this dialogue.
—Meena Dawar, MD, FRCPC
Medical Health Officer

References

1.    Vancouver Coastal Health. Physicians’ update. Accessed 9 March 2016. www.vch.ca/your-health/health-topics/communicable-diseases/for-health-pr... [16].
2.    BC Centre for Disease Control. Communicable disease control manual: Immunization. Section IV: Administration of biological products. Accessed 9 March 2016. www.bccdc.ca/health-professionals/clinical-resources/communicable-diseas... [17]
3.    Public Health Agency of Canada. Canadian immunization guide. Route, site, and technique for vaccine administration. Accessed 9 March 2016. www.phac-aspc.gc.ca/publicat/cig-gci/p01-07-eng.php#rout [18].
4.    Kroger AT, Sumaya CV, Pickering LK, et al. General recommendations on immunization: Recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR Morb Mortal Wkly Rep 2011;60:1-60.
5.    Medicine Plexus. Article: Radial nerve. Accessed 10 March 2016. www.medicineplexus.com/index.php/articles/86-radial-nerve.  [19]
6.    BC Centre for Disease Control. Surveillance forms: Adverse events following immunization. Accessed 9 March 2016. www.bccdc.ca/health-professionals/professional-resources/surveillance-forms [20].