Cardiac Inflammation after COVID-19 mRNA Vaccines: A Global Pharmacovigilance Analysis

ABSTRACT Background To counter the COVID-19 pandemic, mRNA vaccines, namely tozinameran and elasomeran, have been authorized in several countries. These next generation vaccines have shown high efficacy against COVID-19 and demonstrated a favorable safety profile. As widespread vaccinations efforts are taking place, incidents of myocarditis and pericarditis cases following vaccination have been reported. This safety signal has been recently confirmed by the European Medicine Agency and the U.S. Food and Drug Administration. This study aimed to investigate and analyze this safety signal using a dual pharmacovigilance database analysis. Methods This is as an observational study of reports of inflammatory heart reactions associated with mRNA COVID-19 vaccines reported in the World Health Organization’s global individual case safety report database (up to June 30th 2021), and in the U.S. Vaccine Adverse Event Reporting System (VAERS, up to May 21st 2021). Cases were described, and disproportionality analyses using reporting odds-ratios (ROR) and their 95% confidence interval (95%CI) were performed to assess relative risk of reporting according to patient sex and age. Results At a global scale, the inflammatory heart reactions most frequently reported were myocarditis (1241, 55%) and pericarditis (851, 37%), the majority requiring hospitalization (n=796 (64%)). Overall, patients were young (median age 33 [21-54] years). The main age group was 18-29 years old (704, 31%), and mostly males (1555, 68%). Pericarditis onset was delayed compared to myocarditis with a median time to onset of 8 [3-21] vs. 3 [2-6] days, respectively (p=0.001). Regarding myocarditis, an important disproportionate reporting in males (ROR, 9.4 [8.3-10.6]) as well as in adolescents (ROR, 22.3 [19.2-25.9]) and 18-29 years old (ROR, 6.6 [5.9-7.5]) compared to older patients were observed. Conclusions The inflammatory heart reactions, namely myocarditis and pericarditis, have been reported world-wide shortly following COVID-19 mRNA vaccination. An important disproportionate reporting among adolescents and young adults, particularly in males, was observed especially for myocarditis. Guidelines must take this specific risk into account and to optimize vaccination protocols according to sex and age. While the substantial benefits of COVID-19 vaccination still prevail over risks, clinicians and the public should be aware of these reactions and seek appropriate medical attention.