evidence: Objective To summarise the available evidence on the risk of myocarditis and/or pericarditis following mRNA COVID-19 vaccination, compared with the risk among unvaccinated individuals in the absence of COVID-19 infection. [...] There has been an increase in reports of myocarditis and pericarditis following COVID-19 vaccination shortly after several countries expanded immunisation to children and young adolescents.18 19 According to several studies and case series, the highest incidence of myo/pericarditis was found among adolescents aged 12–17 years, and mainly affecting males following the second vaccine dose.9 20 21 The remarkable clinical similarities in patients presenting with myo/pericarditis, the onset of symptoms within a few days following the mRNA COVID-19 vaccine inoculation and the absence of other known aetiologies suggest a possible link between mRNA vaccination and these cardiac adverse events.22 Nonetheless, it is important to point out that occurrence of myo/pericarditis in vaccinated individuals does not immediately imply that the vaccine was the causative agent; it could also be the result of an adjuvant that promoted, reactivated or accelerated naturally occurring myocarditis caused by viral or immune-mediated factors.23