key: cord-0015406-t5xj72xg
authors: Ng, Jia Yu
title: Inadvertent subcutaneous injection of COVID-19 vaccine
date: 2021-02-15
journal: Postgrad Med J
DOI: 10.1136/postgradmedj-2021-139870
sha: b312f764a852782e86b4ea70bdf9fb8b0c2be25d
doc_id: 15406
cord_uid: t5xj72xg

nan

COVID-19 has been the single greatest public health emergency in the history. The global demand for vaccine vastly outstrip available supply during this scale-up period. There is therefore a need to train up more vaccinators to maximise vaccine uptake in short time period.

Like most other vaccines, the COVID-19 vaccine should be given intramuscularly. Muscles have good vascularity, and therefore allowing injected drug to reach systemic circulation quickly, bypassing the first-pass metabolism. 1 Intramuscular injection of the deltoid muscle should be given along a line drawn vertically downwards from the mid acromion. 2 The manufacturers advise that the vaccine should not be injected intravascularly, subcutaneously or intradermally. 3 Injecting a vaccine into the layer of subcutaneous fat with poor vascularity resulting in slow mobilisation and processing of antigen leading to vaccine failure. 4 The antigen may take longer to reach the circulation after being deposited in fat, delaying presentation to T and B cells that are essential for immune response. In addition, there is a risk that the antigens may be denatured by enzymes if they remain subcutaneously for prolonged period. Subcutaneous injections can lead to localised cellulitis, granuloma formation and abscess.

The COVID-19 vaccine has shown to have high efficacy if given correctly intramuscularly. Subcutaneous injection can happen inadvertently (figure 1), affecting efficacy of vaccination and potentiate local adverse events. It is vital importance to reinforce intramuscular injection training with competency assessment at intervals in order to maximise efficacy and maintain public confidence. 

The importance of injecting vaccines into muscle. Different patients need different needle sizes

Best vaccination practice and medically attended injection site events following deltoid intramuscular injection

Information for Healthcare Professionals on Pfizer/BioNTech COVID-19 vaccine

Subcutaneous vaccine administration -an outmoded practice

Contributors JYN contributed in planning, conduct and writing up the work.

The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.Competing interests None declared.

Provenance and peer review Not commissioned; internally peer reviewed.This article is made freely available for use in accordance with BMJ's website terms and conditions for the duration of the covid-19 pandemic or until otherwise determined by BMJ. You may use, download and print the article for any lawful, non-commercial purpose (including text and data mining) provided that all copyright notices and trade marks are retained.

Jia Yu Ng http:// orcid. org/ 0000-0002-5974-6881