Myocarditis in Malta in the COVID-19 vaccination era : a population-based study

Abstract

BACKGROUND: Vaccination against COVID-19 is crucial for controlling this scourge. COVID/vaccination deniers often rationalise their unfounded fears by citing rare vaccination side-effects. One of the most frequently cited side effects is myocarditis, especially in younger persons. Malta has very high vaccination rates. This study was carried out to ascertain whether admissions to hospital for myocarditis changed in any during the vaccination rollout, up to October 2021, when 83.4% of Malta’s population of circa half a million had had their first 1st dose.

METHODS: Malta is served by one large regional hospital (Mater Dei Hospital). Anonymous data for admissions with a diagnosis of myocarditis (ICD I40, I41, I51.4) were obtained for 01/2016-10/2021. Myocarditis discharges and 95% confidence intervals were plotted for 2016-2020. Myocarditis discharges for Jan-Oct 2021 were plotted separately.

RESULTS: There were no outlier values for myocarditis discharges in either direction for any age for any of the two sexes.

CONCLUSION: Myocarditis, independent of vaccination, is commonest in young males, half resolving and some developing dilated cardiomyopathy, possibly leading to transplantation or death. The ongoing mass vaccination with novel messenger RNA vaccines resulted in reports of myocarditis in male teens, this being a rare side effect. The lack of significantly increased rates of myocarditis admission in any age age/sex group in Malta confirms that only rarely, myocarditis may be temporally associated with COVID vaccination which almost invariably runs a benign course and that this risk is very low, far lower than myocarditis due to actual COVID infection.