Association between mRNA COVID-19 vaccination and myocarditis

In early December 2019, the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emerged in Wuhan City, China, causing the first cases of coronavirus disease (COVID-19). It rapidly spread globally, and by 11 March 2020, a pandemic was declared by the World Health Organisation (WHO). The unprecedented global disruption to the spheres of society, the economy, and personal health placed increasing pressure on the development of safe and efficacious vaccines against COVID-19. Of those developed, the Pfizer (BioNTech/Comirnaty BNT162b2) and Moderna (mRNA-1273) vaccines both utilise messenger RNA (mRNA) technology to provide immunisation against COVID-19. Clinical trials have demonstrated high efficacy of these mRNA vaccines in providing protection against COVID-19.1 However, reports from the Centres for Disease Control and Prevention (CDC) have described an association between the mRNA COVID-19 vaccines and the development of myocarditis. International literature has identified myocarditis developing in young males following mRNA COVID-19 vaccination. Preliminary results reported by the Centre for Adverse Reactions Monitoring (CARM) suggest that this adverse effect has also occurred in the New Zealand (NZ) population. The true incidence of post-vaccination myocarditis remains uncertain, as recorded cases rely on passive reporting systems; hence, there may be under-reporting of cases. Therefore, continued evaluation of case reports, retrospective studies, and ultimately an active reporting system, will be required to determine the rate of myocarditis following COVID-19 mRNA vaccination. In the interim, it has been determined that the benefits of the COVID-19 vaccination in reducing the risk of developing COVID-19 outweigh the potential adverse effects of the vaccine.